I had started Dupe Checker at first. This program found a lot of duplicate files at my hard disk. It found 12 mp3 files. When I deleted all 536 duplicate files I got 97 Mb of free space. Then I had started Mp3 Duplicates Finder. This program found 54 duplicate mp3 files. When I deleted 54 mp3 files I got 312 Mb of free space. Note that mp3 files occupy a lot of space whereas for example documents and images are small enough, and removing mp3 files is more efficient than documents and images. Thus Mp3 duplicates finder was more useful for me. Sorry for my english.