Quoted from Dayhuff:
Be very careful in thinking your buying original/one of a kind. There's lots of copies of this sorta thing floating around in the pinball community. Not saying these listings are copies but I'd almost have to see it in person to be certain.
Good to note for any sort of paperwork or artwork coming from any field.
However, as far as I'm aware, the seller is James Lofflin, and he has been selling a variety of original pieces over the past several months to help fund the development of Pinball Circus. While it's still advisible to do your homework, I wouldn't be quite as worried about the stuff he's selling compared to a random/unknown seller.