In today's WSJ, an article headlined "Apparent Hoax Shakes Up World of Classical Music" describes the discovery that a series of CD recordings by Joyce Hatto, allegedly made while she was dying of cancer, were copies of recordings by another artist. Joyce Hatto's husband engineered the copies.
A British classical music magazine, Gramophone, initially broke the story. An American CD listener discovered the hoax, and his subsequent probing of the matter led to the Gramophone article. But the Gramophone article does not detail just how the listener first knew something was wrong. The WSJ article does.
When the CD listener inserted the disc into his Apple computer, he "was surprised when . . . iTunes software identified it as a CD by another pianist," Laszlo Simon. The American followed up the anomaly, and that led to the investigation by Gramophone.
The WSJ article explains the iTunes technology that enables it to recognize
a CD by querying a database maintained by a company called Gracenote, of Emeryville, Calif. Gracenote recognizes a CD by the number of tracks it has and the length of each of those tracks; when combined, the two form a mathematical fingerprint that Gracenote says is essentially unique for CDs with more than about five songs.
The Gracenote software was able to recognize the CD of the real pianist, even though the husband of the dying pianist had shrunk or stretched some of the tracks.
There is a lot on the internet about this hoax. You can start here or simply google "hatto simon hoax".