If you are running iTunes 11.0.1 (and higher), iTunes will automatically help you weed out those duplicate items from your iTunes library. If you are running iTunes 11, you’ll see that this feature isn’t available. So to remove duplicate tracks from your iTunes library, the first thing you need to do is update to the latest version of iTunes.
If you use iTunes as your default music library manager, and if you’ve enabled iCloud backup/sync, there’s a strong chance that you end up having a few duplicates.
Also, when you move around your music files a lot (or change libraries), you might end up with a few duplicate entries on iTunes.
If it’s just a case of folders/libraries, cleaning up your iTunes and then re-linking it to the music folder usually does the trick but that might not be enough in other cases.
How to Delete Duplicate Music Files from iTunes library
Step #1. First off, make sure you’ve got the latest version of iTunes.
Step #2. Now, open iTunes.
Step #3. Click on “View.”
Step #4. Click “Show Duplicate Items.”
Step #5. Also make sure Music in the Cloud is visible. You should see a “Hide Music in the Cloud” option.
Step #6. iTunes will filter the content and show only those tracks that have duplicates. Both the tracks will be listed so you can easily remove the one that you don’t want. Now, select the duplicate songs and hit delete.
Sometimes, iTunes also shows multiple versions of the same song (remix, reprise, etc.) Make sure you don’t end up deleting them in a hurry.
If you want only to choose exact duplicates, you should press Alt when clicking View and continue to press is when you click on “Show Exact Duplicate Items.”
This works good, but sometimes, if your albums and tracks aren’t named properly, even this feature won’t work well. This is often the case because you’ve got more music from outside iTunes (with/without DRM etc.)
There are software options that work better than iTunes. TuneUpMedia is one software we’ve heard very good reviews about so you could try that.