using finder to identify duplicates in music

The apple store migrated all of my data from my PC to my MBA a year or two ago. My iTunes library was and still is a mess. I've eliminated all duplicates identified via itunes BUT I still have lots of duplicates. (I've tried duplicate utilities but don't have enough space (I think that was what I didn't have enough of) to run the program all the way through) So I've started going through my music library in Finder. I'm finding multiples of folders and of individual MP3's. Using a split screen with Finder and iTunes, I've gone through 100 or so tracks and deleted duplicate folders and duplicate MP3's. Seemed to be working until I discovered that some of the music is missing even though I made sure to leave one of each MP3. HELP!!! THANK YOU!!!!!!