Apple is back with a handy how-to on finding duplicate songs (or videos) in your iTunes library. This is timely for me as some weird combination of MobileMe prefs sycn, Home Sharing, SuperDuper cloning, and iTunes 9.1.1 resulted in my main iTunes library disappearing, and the restore left me with multiple copies of multiple songs. Here's the recommended fix:
Begin by selecting Music in your iTunes Library, then choose Display Duplicates in the File Menu and sort the resulting list by Name. It will display only songs with names that exactly match the names of other songs.
Not all will be duplicates, of course. For example, some might be covers, and others could be different performances by the same artist. To help identify actual duplicates, put the Time column right next to the Name column in your display. (Just grab it by the title and drag it over there. And by the way, hiding the Artwork column will make it easier to spot what you're looking for.) Identical names with identical playing times are highly likely to be duplicates and you can then choose the one(s) you want to get rid of. When you're done, click Show All at the bottom of the window.
There's also a quick way to spot duplicates of the exact same song from the exact same album by changing the Display Duplicates command to Display Exact Duplicates. In iTunes for Windows you do this by holding down the Shift key when you click the File menu, and you can then move down the menu to select that command. On the Mac, hold down the Option key while you select the Display Duplicates command and it will change to Display Exact Duplicates. You'll still need to look carefully before deleting because some albums contain more than one version of the same song, but most of what you'll see will be true duplicates.
I nuked and started over, which was a slower and more aggravating process, so kudos to Apple for surfacing how to articles like this one. If you've dealt with duplicate songs -- or movies, TV shows, podcasts, etc. -- in your iTunes library and have ninja tips of your own to share, let us know in comments!