I had a similar situation happen to me on eBay down here in Australia a few years ago. The seller was selling multiple brand new sealed copies of Beat 'em and Eat 'em, Custer's Revenge and Bachelor Party. They didn't live far from me so i went to check them out. From what he told me they had bought a few pallets of imported merchandise that had been sitting in a warehouse for 30+ years. When i checked them out i could tell straight away they were original. They probably had 100 games, 6 copies of each game in cardboard boxes. I ended up buying a few off them, including a big box (see pics) I'm assuming the same thing has happened, they have come across old new stock of them from somewhere.