Let's be helpful and underline the weeak points.
I tried this on the very little library on my MBAir, results:
-6 duplicates, in detail:
-the first 3 were two different versions 29 seconds different (same title and author) and, even worst, one was a VIDEO!, so they're not a real duplicate.
- the last 3 were the video and the pure audio version, same time, this time, nevertheless not reason enough to consider them 'duplicates'.
I already used other duplicate finder apps and I deleted unfortunately some duplicate, yes, but of a corrupted file (the ones who can't be played till the end and let iTunes jump to the next one, another very annoying still not solved problem of iTunes!).
Before to consider 'duplicate' a file, it should be deeply analyzed, if not, it should be named 'similar' and, possibly, listed IN WHAT they differs and in what they're IDENTICAL.
Tags and slightly different names or infos could result in a slightly different size of the whole file while the content is identical, in this case list as identical file with different attachments.
Shortly, this program still needs a heap of work to match the real needs of the rest of us, even more if we have to work on a real LIBRARY of tenth of thousands of files or more!

Normally i wont take the time to register to a site like this just to post a review, but this program is SOOOOO HORRIBLE i had to take the time to save you from wasting your time as well. This program is as worthless as a 1 legged man in a 3 legged race. I have over 30,000 tracks in my iTunes library and this program takes nearly 3 hours to start. Yeah 3 hours im not joking. If and when i have time to get this program to start it usually has a "Not Responding" error and closes out. Not only that but when it does get to the mainscreen there is no "fast" way to get this program to delete all your duplicates. I have nearly 2,000-3,000 duplicates and it wants me to select these duplicates one at a time. Do you know how long that would take? WTF am i supposed to do take a whole day off of work so i can get this program to function? This program is a HUGE waste of time and money. Granted the license for this program is only $7.95, but i would have rather thrown a $10 bill in the toilet.