On three separate occasions over the last week, I've noticed new protected AAC audio files (.m4p) files magically appearing in my iTunes library. These are for songs that I've had for a while, so it isn't associated (as best I can tell) with new purchases. The original purchased AAC audio files (.m4a) remain in my library, so I've effectively got duplicate songs -- one subject to DRM, and one not. Obviously, I can simply delete the .m4p version from the library and my hard drive, but I'm wondering if anybody else is seeing this phenomenon and has an explanation.