In iTunes, click the "Music" category under the Library section from the selector on the left. You should now see all of the music items that are in your iTunes library. Now click File > Show Duplicates. Any duplicate songs that are in your library will show up, and you will be able to delete the ones that you don't want any longer. To hide the duplicate song list, click the "Show All" button at the bottom of the window (or click File > Show All). You can use this same method for Music, Videos, and TV Shows. It will also work in any playlist.
Using the built-in iTunes feature is nice, but it can be very time consuming -- especially if you have thousands of songs, videos, or TV shows. In this case, you can use an application like iDupe (which costs $8US). iDupe gives you a ton of options for deleting duplicate songs in iTunes.
Do you know another way to delete duplicate iTunes songs? Know of another application to delete duplicates? Tell us in the comments!
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