Duplicate Media Finder - Duplicate Media Finder locates and deletes identical files and similar media
Idupe - iTunes has a “Show Duplicates” command, but it is of limited use.
dupeGuru - dupeGuru is a tool for finding duplicate files on your computer.
Tune Sweeper - Show duplicates in your Music library. Automatically select which duplicates to keep and delete based on your preferences. Remove duplicates with one-click from your iTunes or Music app library.
Duplicate Cleaner - Duplicate Cleaner: the fastest and most popular tool for finding duplicate files. Over 1 million downloads: Get your copy now! Free and Pro versions available.
Leawo Tunes Cleaner - Leawo Tunes Cleaner is a powerful iTunes cleanup tool, which can help you to delete duplicates in iTunes and get album artwork for iTunes music files.With it,you can clean up iTunes music library fast and comprehensively.