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.
dupeGuru - dupeGuru is a tool for finding duplicate files on your computer.
Dupe Eliminator for iTunes - iOS, iPad, iPhone, iPod Touch, iTunes, iTunes software, Software for iTunes, mobile iOS apps for iPad, iPhone and iPod Touch. Remove iTunes duplicates. Stream iTunes Music Library. Super iTunes Suite of useful tools.
AllDup - AllDup is a freeware tool for searching and removing file duplicates on your Windows computer.
SongGenie - SongGenie analyzes, identifies and repairs your mp3 tags and names.
Czkawka - Multi functional app to find duplicates, empty folders, similar images etc.