Very weird

The DVD of Phantom of the Paradise that I picked up at Newbury Comics turned out, when I put it in the player, to actually be a copy of Predator. The printing on the top side of the disc is right, but the contents aren't. I've never seen this flavor of production screw-up before. Did they both come out on DVD at the same time? They're both Fox films, but that's the best idea I can come up with.