I have a feeling that some prankster opened up some of those UMD cases and flipped the UMDs around, making it appear that all those UMDs are shiny on "both sides".
Although it would be nice, I seriously doubt that they are real.
But what use would they be without a burner to burn them?
there are no UMD burners in existance. the discs are pressed like a CD or DVD, and then inserted into the UMD case.