Last updated May 8, 2026.

Quick Start

Here's a basic rundown of how to use Dupin. Dupin is quite flexible so be sure to try all the various settings and options.

• Step 1.
• Launch Dupin. It will immediately begin indexing your music library.

• Step 2.
• Get Duplicates

After the initial indexing completes, select the "Get Duplicates" command from the File menu—or press Command-G or use the "Get Dupes" toolbar icon—to initiate the processing for duplicates. This panel will appear: (If this is the first time you have launched Dupin, it will do this automatically. "Get Duplicates at start up" can be switched off in Settings.) The Criteria checkboxes are default set to Title, Artist, Album and Track Number. That means that only tracks with matching title, artist, album and track number tags will be considered duplicates of one another. Click the "Get Dupes" button in the panel or press return. In a moment, Dupin will sort the tracks into "Dupe Groups". Each Dupe Group contains duplicate tracks based on the selected Criteria.

• Step 3.
• Filter Controls

The Filter Controls determine which single track in a Dupe Group should be the "Keeper". Select the "Filter..." command from the File menu—or press Command-F or use the "Filter" toolbar icon—to display the Filter Controls window. Filter Controls Window: Set the Filter Controls options you require for filtering. Click the "Filter" button. Any track(s) in a Dupe Group not matching your Filter Control Settings will be marked as a non-Keeper. Filter Controls can be re-set and the Dupe Groups can be re-filtered any time. Additionally, use the Show Info Window to scroll and inspect tracks to set Keeper status manually. For more information, see Using the Filter Controls.

• Step 4.
• Purge and Purge Test

Important Sync Library Information

Sync Library works in conjunction with Cloud to provide access to your Music tracks from all of your computers and devices.

Presumably you have a basic understanding of how Sync Library works if you are using it.

Tracks that Dupin detects as "Remote" will be colored blue—or light blue if designated as a non-Keeper.

Important considerations regarding Dupin:

Purge Sync Library tracks

If Sync Library is enabled, Dupin will not be able to delete tracks from the Music library. Such tracks must be manually batch-deleted as described below. Fortunately this is a very easy and fast procedure:

Purchase and Register

The demo version of Dupin will only display the first 20 Dupe Groups it finds in your Music library and only allow one Purge per session. After you purchase a registration code Dupin will display all the Dupe Groups it finds enabling you to work with all your duplicates in one session.

Main Features

Using the Criteria Panel

The Criteria Panel matrix tells Dupin which track tags to consider when evaluating tracks as duplicates of each other; it is how you define "duplicateness". This provides a powerful yet flexible way to discover various types of duplicate tracks. Since the definition of "duplicateness" can vary from user to user or situation to situation, Dupin leaves it to the user to define it. To Select Criteria: Click on the button next to a Criteria Tag's checkbox to check or uncheck it. Checkmarked Criteria Tags will be the only tags evaluated when Dupin searches for duplicate tracks. That is, two or more tracks will be considered duplicates of each other if only those tags contain identical data. You can set whether or not to use case sensitivity in Dupin's Settings. Your Criteria Matrix settings will be saved between uses of Dupin.

"Filename" as Criteria Tracks that are duplicates of each other may not have the same filename. If "Filename" is selected as Criteria Dupin would not consider these tracks as duplicates: An AAC file and a MP3 file, for example, whose tags may be identical will always have different filenames by virtue of each having different file extensions. Quite often, Music will append a number to a filename—when the file is initially added to Music—to differentiate it from a file that is already in its database with the same filepath and filename. A track's Name and its file's filename are frequently not the same. Thus, two or more tracks with the same Name could be thought of as duplicates even if each of their filenames are different. ...and so on. Use this setting thoughtfully.

"Time Criteria matches +/- seconds" in Preferences: When "Time" is selected as Criteria, Dupin will consider two or more tracks' times a match if their times are exact to the second. You can "loosen" this setting in Dupin's Preferences such that two tracks' times must be within a plus/minus range of seconds (:01 ≤ n ≤ :10) of each other to be considered a match. By default, Dupin is set to use +/- 3 seconds.

Using the Filter Controls

The Filter Controls window provides you with versatile options for globally selecting the "Keeper" in every Dupe Group.

Once the Dupin window is filled with Dupe Groups, activate the Filter Controls window by clicking on the "Filter..." command in the File menu—or by pressing Command-F, or by clicking on the "Filter" toolbar icon.

Adjust the settings to your liking and then click the "Filter" button—or press Command-F again or Return. In a few moments, each Dupe Group will be filtered and a single track in each Dupe Group will be designated as a Keeper.

To reset all tracks to Keepers anytime, click the "Reset to All Keepers" button.

You can choose to filter tracks automatically after Dupin has gotten dupes in Settings.

Additional Options

You can refresh the Keeper status of all tracks in current Dupin window by clicking on "Checkmark All/Clear Checkmarks" (one or the other option will be displayed depending on how you designate Keepers in Settings) in the View menu or by pressing Shift-Command-X. Then you can run Filter again using different settings.

Your Filter Controls settings will be saved between uses of Dupin.

Using the Purge and Purge Test Controls

The Purge tool will delete all non-Keeper tracks from your Music library. Optionally it can move their files to the Trash, delete the files immediately, or move the files out of their current location to a user-selected folder. This operation cannot be un-done so be sure your Keeper tracks are selected correctly. To feel safer, run "Purge Test..." first. It does everything the "Purge" command does except delete or move files. And will create a report listing what would have been moved or deleted in a real "Purge".

Be sure to have filtered the Dupe Groups, either automatically by the Filter Controls or by clicking their checkmark buttons directly in the main window or through the Show Info Window.

Select "Purge..." from Dupin's Tools menu. This Purge Options panel will appear:

• Trash files - the files of the non-Keeper tracks will be moved to the Trash folder. Files can be recovered from the Trash if necessary.
  
  Delete files immediately — bypass Trash - uses the UNIX "rm" command to delete the files unrecoverably. You made need to use this if your files are located on a server where Trash is not supported, such as some NAS drives.


• Keep files - files will remain in their current locations.
  
  Move files to folder: - files will be moved from their current locations to the single selected folder.


• Delete any empty playlists after Purge - if it happens that, after a Purge, a playlist contains no tracks then it will be deleted.


• Create text file listing Purged tracks info - when checkmarked, will create a text file listing track informtion in the folder location selected. (This is the same location that can be set in Settings.)

• NOTE: If Sync Library is enabled you will not see the "File Purge Options" settings sheet. Instead, tracks will be copied to a discrete playlist for manual batch-deletion after the Purge.

Click the "OK" button when ready to begin. Purging ensues immediately.

If Sync Library is enabled, Dupin cannot delete tracks from the Music library. Such tracks must be manually batch-deleted as described below. Fortunately this is a very easy and fast procedure:

Deleting Sync Library tracks after a Purge:

1. During the Purge operation Dupin will copy tracks designated as non-Keepers to a new playlist it creates in the Music app named ***Dupin Purge Tracks***.
2. When the Purge operation is complete, select the ***Dupin Purge Tracks*** playlist in the Music app.
3. On your keyboard, press Option-Delete (press and hold the "Option" key and press the "Delete" key). As described in Music > Help > Keyboard Shortcuts, this is the shortcut for deleting the playlist and the tracks it contains from your Music library.
4. Follow the prompts displayed by Music for deleting the playlist, deleting the tracks, and optionally Trashing the files and/or removing the files from the cloud.

The ***Dupin Purge Tracks*** playlist is re-created on each Purge operation. If you do not Option-Delete it after a Purge the tracks it contains will remain in the Music library.

Other Tasks and Commands

Show Info

The Show Info Window not only displays all available tag data for the selected track, it also allows the Keeper status to be chosen and serves as a "navigator" to scroll the list of tracks in Dupin's main window one at a time.

Use the up and down buttons or your keyboard's Up Arrow and Down Arrow keys to scroll through the list.

When "SCROLL LOCK" is on, tracks will be selected as you scroll.

The "Scootch" button, between the up and down buttons, will scroll the currently selected row to the middle of the main window.

Search

Display only the tracks matching the entered search text, with options to search just the Title, Artist or Album.

Export

Creates a text file listing what you see in Dupin's main window.

Remove "Dead" Tracks

A so-called "dead" track is a track entry in the Music library whose associated audio file is either missing or inaccessible when the Music app launches. There's nothing to play if Music can't find the audio file.

Dead tracks are indicated in Music with a circled "!".

What might have happened is 1) a track's file had been Trashed outside of Music—rather than by deleting it and its file in the Music app so that its database can be updated with the change—or 2) the external volume that a file resides on is un-mounted or otherwise unavailable. Or 3), any number of "no user-serviceable parts inside" violations of the Media folder.

Of course, Music can't "know" if a file has truly been "disappeared", accidentally or otherwise, or is just temporarily inaccessible. Only you know this.

Important considerations regarding Dupin

Dupin is able to detect dead tracks in your library during the Get Dupes operation. Dead track entries will be colored red in Dupin.

Because the existence of a dead track's source audio file is, at best, ambiguous, Dupin would prefer to ignore them. Thus:

• During a Filter operation - dead tracks will be designated as non-Keeper tracks automatically.

• During a Purge operation - Dupe Groups containing any dead tracks will be ignored.

However, you can remove the dead tracks from Dupin so that they aren't a distraction. Additionally, you can delete the dead tracks detected by Dupin from the Music app.

Removing dead tracks detected by Dupin:

• After performing a Get Dupes operation any dead tracks found will be colored red.
• Select "Remove Dead Tracks..." from Dupin's Tools menu.
• In the drop-down that appears, click the "Proceed" button.
• Dead tracks will be removed from Dupin and any Dupe Groups containing fewer then two tracks will disappear.

To additionally delete these dead tracks from the Music app:

• In the drop-down that appears, put a checkmark in the box next to "...and delete them from Music" and then click the "Proceed" button.
• Dead tracks will be removed from Dupin and deleted from Music. This operation cannot be un-done.
• This only deletes the dead tracks detected by Dupin. Other dead tracks may still exist in your Music library that aren't duplicates. I recommend my AppleScript tools Super Remove Dead Tracks and List MIAs for in-depth dead track elimination.

Using "Show Only Groups..." Filters

Dupin normally shows all the Dupe Groups it finds. But in the interest of more granular control, you can select to show only the Dupe Groups that contain:

• ...at least one "dead" track
• ...at least one local track
• ...at least one Cloud track

After performing a Get Dupes, the following menu commands will be enabled:

Use the "Show All Groups" to restore the default view of all Dupe Groups.

Settings

Access the Settings panel from the Dupin menu or by pressing Command-comma.

General

• Automatically check for updates
• Check for an updated version of Dupin whenever it starts up. Otherwise, you can check for an update using the "Check for Update..." command in the Dupin Application menu.

• Show Help buttons
• Several windows display Help buttons to give you access to that window's function in this Help book. You can toggle this preference to show or hide them.

• Message logs location
• Save a text file listing information about deleted tracks to this location. You can select a folder to save the text file by choosing "Select other..." from the popup. (This is the same folder that can be set during a Purge operation in the "File Purge Options" sheet.)

• Reset Warnings (at bottom of panel)
• Various warning messages that have been supressed—by virtue of having their "Do not show this message again" buttons clicked—will re-appear after clicking this button.

Getting Dupes

• Get Duplicates at startup
• Immediately initiate getting duplicates at startup using the last-set Criteria panel settings.

• Text comparisons are case sensitive
• Checking this will oblige Dupin to compare text in tags in a case-sensitive manner while Getting Dupes.

• Use bit rate rounding to account for ABR encoding
• ABR (Average Bit Rate) is the default encoding mode for AAC files. This means that files imported or converted as AACs in the same session will have slightly different bit rates which can vary from the selected bit rate by as much as plus-or-minus ten percent—although not as much as files encoded using VBR (Variable Bit Rate).
  
  When this preference is checked, and "Bit Rate" is selected in the Criteria Panel matrix settings, Dupin will consider that two or more bit rates are a match if they can round to (ie, are within a minimal range of) the nearest traditional constant bit rate (96, 128, 160, 192, and so on). For example, files encoded at 124 kbps, 126 kbps, and 130 kbps would be considered the same because they are within the range of 128 kbps. If this preference is not checked, two or more files' bit rates must be exactly the same in order to match.
  
  Bear in mind that files encoded at different bit rates will have different sizes, too. Dupin does not perform approximate size matching.

• Time Criteria matches +/- seconds
• Used in conjuction with the "Time" Criteria. Check this to enable the horizonal seconds slider and then use the slider to designate a number of seconds between 1 and 10. When "Time" is selected as Criteria, Dupin will consider two or more tracks' times a match if they fall within the number of set seconds—plus or minus—of the other(s). Thus if the seconds slider was set to 2 or above then 3:04 and 3:06 would be considered a match. (A setting of 4 seconds is probably all that is necessary in most cases.)
  
  When unchecked, two or more tracks' times must be exact to the second to be considered a "Time" Criteria match.

Filter Controls

• Designate "Keepers" as: Checked/Unchecked
• Dupin's default behavior is to use a checkmark to designate the Keeper track within a Dupe Group. However, some users prefer the opposite configuration whereby a Keeper is designated by being un-checkmarked. After toggling this setting the new configuration will take effect the next time you start Dupin. In any case, the text color of non-Keepers is always lighter than the text color of the Keepers.

• Automatically filter after Getting Dupes
• Check this to automatically apply your Filter Controls settings after a Get Dupes operation.

• Keep Filter Controls window open and on top
• When this is checked the Filter Controls window will remain open rather than be dismissed after Filtering.

Email Support

I'm not the Apple Answer Man, but I can help you if you have questions about Dupin. Contact support AT dougscripts DOT com