Re-importing your iTunes library can be a bit of a mess. M3U files from the past always come back to haunt me. Between M3U files and compilation albums, I often find quite a few duplicates in my library, and getting rid of them has always been a pain.
Apple provides a way to display duplicates in iTunes, but it usually does a mediocre job of discerning between actual duplicates and tracks that have the same meta tag information. Turns out the option key has another hidden trick up its sleeve: revealing “exact” duplicates.
While in iTunes, select the File Menu, then hold down the option key. The Display Duplicates menu item should turn into Display Exact Duplicates. It’s a much better search, and should reveal songs that are the exact same, as opposed to songs with the same name. There’s a lot of hidden features around OS X that appear when you hold down the option key. We even have a post highlighting some of them.