I have been experimenting with the unregistered version of Perfect Tunes. The De-Dup option seems to be a bit erratic. Some of the duplicates which it identifies are genuine but for example I have a number of different recordings of classic piano pieces such as Beethoven's Diabelli Variations. When comparing FLAC files, De-Dup manages to convince itself that the same variations from discs by Schnabel, Brendel & Lewis are duplicates. Similarly, it identifies movements of Beethoven Piano Concertos played by different orchestras and soloists as duplicates. While they are very similar in length, I find it hard to believe that they are identical to one frame. All of the CDs were ripped using dbPoweramp CD-Ripper and were checked against the AccurateRip database when created. The pieces are not identical.

Another oddity is that it believes that all of the tracks from a recording of Bartok's Miraculous Mandarin are duplicates of each other. This appears to be a misinterpretation of the original source information. This disk was one of a very small number of Naxos DVD-Audio disks that I purchased and converted to WAV files and then to FLAC.