I don't think you'll ever get to the bottom of it. Let go, and move on... :-) That said, you might want to Google the specific DVD to see if others have experienced the same problem. Fwiw, I'd guess it's a faulty batch. Amazon are pretty careful about who they'll allow to trade using their name, and would come down like a ton of bricks if there was any suspicion of a seller involved in piracy.
The Evil Within 2 review-in-progress