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.
TuneUp - TuneUp makes your music fresh and clean!
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.