My buddy Andy did the "write exams for other people" thing. He wrote the English 100 final exam about 10 times. Of course they check ID. The always did. You left your student card on your desk and while you were writing someone would walk up and down the rows checking ID. The thing is, Andy was Han Chinese, about 5'6" with medium length dark hair and glasses, so he looked like every second guy at the Uni who was writing the test.