Recently I've discovered an interesting tool called Phelix, it seems to be a successor of a freeware Seek & Destroy Music Duplicates. Phelix is unique in one feature: it actually identifies duplicates by listening to music. How it works, I don't know, but it's surprisingly fast (from the aspect of fact that it is obviously processing mp3 audio). Lots of zombie-duplicates have been found, invisible for conventional tag-matchers (50 in my master collection of 3000 songs). Tool selects also songs with sound similarities. Conventional tag-matcher is powerful and very fast. I don't know if there is any better music dupe-killer currently on the market.
