If you’ve done anything like consolidating your music library the music/iTunes may well have duplicated it.
Find you music library location (if you don’t know where it is open Music, then right click any song and it will give you an option to show in finder - thats for Mac but I’m sure windows will be similar)
Your music files should be stored in a folder called Music. Look in that folder, and see if it contains another folder also called Music.
If it does you may find all the duplicates in there.
If that’s not it, try the Bliss app which has some good features for cleaning up the mess that iTunes makes of your music!
Sent from my iPad using Tapatalk