I just tried iDupe. First I tried my whole iTunes library and it gave me a warning that it should only be used on small selections of files at a time. I then tried iDupe on a small selection (251 files) that I knew had a lot of duplicates. iDupe took over twenty minutes to look at the 251 songs and find 48 duplicates. It took over my computer during the entire search. I could not quit iDupe, access the finder or anything else on my Mac until it finished. I then told it to delete the 48 duplicates it found and once again froze me out of access to anything on the Mac and after 20 more minutes, it got stuck requiring a force quit and relaunch of the finder. This program has potential, but until it becomes reliable, can handle larger numbers of songs, and doesn't lock you out of the computer during operation, I can't use or recommend it.