The simplest explanation is that it *is* a prototype of the new iPhone, and that it *was* accidentally left in a bar.
I agree. Think of how difficult it would be to pull off this kind of counterfiet. The person would have to have somehow gotten access to an advanced protype design casing, design buttons and custom chips and batteries for the inside of the device. There are easier ways to fool folks on the internet. It takes about as much skill as manipulating a photograph in photoshop.