<p>What happens if you sign up for three SAT IIs and only take two on the test day? Do your scores still get cancelled even if you don't write anything about the third test on your answer sheet and you bail right after the second?</p>
<p>No nothing happens, they just score the two tests that you took. You can sign up for what tests you plan to take beforehand, but come test day you can take as many or as few as you want, or swap them out for that matter.</p>