How many duplicate tracks do you have in your iTunes library?
Duplicates in itunes are easy to find: Open itunes (9.0 or later) and under the File menu you will find the item: Show Duplicates. As an extra feature if you shfit+click on the File Menu (in Windows or you click on the File Menu and then you hit the option key on Mac) the same item changes to: Show Exact Duplicates, which is an excellent feature since duplicate track names doesn't always imply duplicate versions of a song (i.e. a live version and a studio version, etc).

Duplicate tracks are not the problem, though. It's the duplicate files that are taking lots of disk space. Removing duplicate tracks from the disk could save you several gigs of space. If you run the "Show Exact Duplicates" you will get a list of all the tracks that are duplicated in your library therefore: if you delete all the tracks on that list you will get rid of all the tracks! You will not have any versions left of the tunes!

A manual solution #1: is to choose one by one which one of the duplicates you want to keep, (for example keeping the high quality versions such as aiff and deleting the mp3 versions, or the opposite to save even more space) and delete the rest. For some itunes users with 5000+ duplicates this task could take several days! also taking the risk of deleting a wrong version or even worse, all of the versions.

A manual solution #2: you can highlight all the tracks in your library and drag them from iTunes to a new folder on your drive, which will make a copy of the library without duplicates. Then you can delete all the tracks from the library and you hard drive. Then import the folder back into iTunes. You will need of course, double the amount of space while you do this and you will not be able to make a decision in which files to keep.

For a fast and effective way of deleting duplicates in iTunes: Export your Dupllciates as a Plain Text File, upload it to our server here and receive your mdeldupfile