How? - Some kinda litmus test to show your love for the president before you can get in? This is a convention. People are supposed to come to it.
It doesn't surprise me that a couple people out of tens of thousands managed to get passes.
Hiya, btw.
Easy: the pass should have your name and your hometown on it -- that's easy. The delegates should have been known. Match that up with official photo ID - driver license. Check 'em at the door. This is what they do at the airport. Knowing that this place is a target, you gotta do something...