I've had to make some actual CD's out of my own music from MP3's just cause it was what I had available at the time, even though I have the original 16 bit wav files (yes I still record in 16 bit, don't go there unless you are willing to donate a newer interface ).
In fact, there are a couple of songs to which I only have an mp3 now as the original sources are looong gone.
Not that big of a leap to imagine that someone had the crazy idea to do this and all they had availabe were some mp3's on someone's phone, which they turned into wavs, but then, you know, OGG! and well...
Making music can be crazy like that!