Do they record names of guests? It would take two seconds to ask the NJ DMV if someone by that name exists. If they don't, then the ID was probably fake. If there is someone by that name, showing the real ID photos to the hostel receptionist would quickly clear up whether the ID is fake or not. The receptionist flirted with him and got him to show his face so there's a good chance she'd be able to look at some photos and say whether any of them look like the guy.