When you sign up to take the SAT, the student uploads a photo of himself/herself which is printed on the admission ticket. You then have to bring an official photo ID (like a drivers license or passport) with your admission ticket. The two documents are examined before being allowed entrance to the exam. So, yeah, it would be possible to falsify these but difficult and take some serious time and effort. I think this generally provides good exam security. I mean, it would be tough to have a 30 year old man show up to take the exam for Felicity Huffmann's 18 year old daughter lol.