Dupin is the iTunes duplicates manager.

New in version 2.4:

• Can detect if iTunes Match is enabled
• Addresses issue of having to individually acknowledge deletion of each track when iTunes Match is enabled
• Can identify iTunes Match “cloud tracks”
• Adds column header contextual menu to show/hide columns
• Fixes text coloring issue when window not frontmost
• Updates names of columns for parity with modern iTunes
• Other minor enhancements

Dupin v2.4 is a free update for registered users of v2.x.

• Very quickly find all sets of duplicate iTunes tracks based on your choice of criteria
• Select the “Keeper” tracks from among a number of duplicates automatically using a variety of versatile filtering options
• Consolidate the play, skip, and ratings information from all tracks in a Dupe Group to the single “Keeper” track
• Re-populate iTunes playlists replacing “non-Keeper” tracks with “Keeper” tracks
• Remove duplicate tracks from iTunes and send files to the Trash
• Manage intentionally duplicated tracks
• Copy tracks to new iTunes playlists
• View duplicates in non-loaded libraries created with iTunes’ multiple library feature
• View duplicates in iTunes libraries on other machines on your local network
• Sort tracks and view track info
• Export a list of duplicates to a text file
• Locate tracks in the Finder and in iTunes
• Audition tracks

New in Dupin v2.3:

• Compatible with OS X Lion
• Fixed issue with delays caused by slow screen redrawing. Most operations will be noticably more responsive.
• Most operations can now be performed on discrete Search results (eg, Filter just the Search results).
• No longer necessary to confirm changes when closing Selection Window as these changes now happen “live”.
• Minor enhancements to improve overall performance.

This version is a free upgrade for registered users of v2.x.

Well now I’m pleased to announce that Dupin Lite, a brand new lite-sized version of Dupin, is available exclusively on the Mac App Store. Dupin Lite has the same core functions as Dupin but with fewer power-user features. And a lighter price. Dupin Lite is just $7.99 in the Mac App Store.

Of course, Dupin is still available when you need to do some heavy lifting (re-playlist, consolidate history, library profiling, etc). But for a not-so-heavy price of $7.99 you can start cleaning up your iTunes library by removing duplicate tracks with Dupin Lite.

Dupin is your iTunes duplicates manager.

Dupin finds sets of duplicate tracks in iTunes based on the criteria you choose. It can then automatically select the “Keeper” tracks from among the duplicates using a variety of versatile filter options. Dupin is flexible, fast, and easy to use.

With Dupin you can:

• Locate, sort, filter, and purge duplicate tracks
• Preserve play history and ratings
• Re-populate iTunes playlists
• Manage intentionally duplicated tracks
• Copy tracks to new iTunes playlists
• Audition tracks
• …and much more

New in version 2.2:

• Added preference to set small/large text-size
• Text color of track rows designated as non-Keepers will be displayed lighter than text of Keeper track rows
• Some of the GUI now rendered with WebKit
• Updated playlist and library icons to iTunes 10 monochrome-look
• Fixed a bug that might prevent Filter Controls window from staying frontmost (when preferred)
• Fixed an issue that might cause the Time column to mis-sort very short tracks
• Fixed an issue that prevented newly added toolbar icons from becoming enabled right away

This is a free update for registered users of v2.x. For more information visit the Dupin product page.

Dupin is your iTunes duplicates manager.

With Dupin you can:

• Very quickly find all sets of duplicate iTunes tracks based on your choice of criteria
• Select the “Keeper” tracks from among a number of duplicates automatically using a variety of versatile filtering options
• Consolidate the play, skip, and ratings information from all tracks in a Dupe Group to the single “Keeper” track
• Re-populate iTunes playlists replacing “non-Keeper” tracks with “Keeper” tracks
• Purge duplicate tracks from iTunes and send files to the Trash
• Manage intentionally duplicated tracks
• Copy tracks to new iTunes playlists
• View duplicates in non-loaded libraries created with iTunes’ multiple library feature or iTunes Library Manager
• View duplicates in iTunes libraries on other machines on your local network
• Sort tracks and view track info
• Export a list of duplicates to a text file
• Locate tracks in the Finder and in iTunes
• Audition tracks

New in Dupin v2.1:

• runs under Snow Leopard or better only
• adds aproximate time matching for Time Criteria (settable to :01 ≤ n ≤ :10 seconds)
• adds File Path column to main table
• made task additions to contextual menus
• some warning dialogs now have suppression/reset options
• “Search” configurable with categories, re-located to toolbar
• other minor GUI improvements and alterations
• speed enhancements
• addresses toolbar customization issue
• addresses threading issue
• addresses memory leak issue

More information and download links are here.