This doesn't add anything that I can see beyond what iTunes own "Show Duplicates" command already does. It does have the option to search for duplicates on an iPod, which might be useful if you manually manage your iPod, but not doing this myself and that may also "duplicate" iTunes own
function. A much better option is iDupe, which does what is really needed: isolate a set of potential duplicates and pick the best one according to a number of options, and then give you the choice to delete all but that one. It also will deal with a large selection of tracks at a time, so you don't have to manually push delete for each one, while still giving you the chance to adjust which track(s) to keep first. iDupe also lets you retain stuff like played count, ratings, playlists, etc. It also deals with dead tracks a lot better, and includes fuzzy matching. Moreover not only is it cheaper, you can pretty much use it unrestricted for as long as you want before paying for it. The thing is neither Dupes Barrier or iDupe work unless your ID3 tags are somewhat accurate. If you want music fingerprint matching you have to go with something like Phelix, which I haven't tried, but by its very nature would have to be incredibly slow and even the description page for it is a major CPU hog.