Op,
Keep in mind that some colleges (Yale, Penn) want all testing history and no score choice.
Back when dinosaurs roamed the earth, we took the SAT in the morning, had a lunch break, then took the Achievement Tests, as they were callled then (3 of them, IIRC) in the afternoon.
And even the high-achieving, top-of-the-class kids only took the SAT once.
^^High five momcat2; we did the same. One-shot deal; no do-overs.
Somewhat similar, but in the late Cretaceous, I took the SAT in March of my junior year and the Subject Tests (3 at once) in the fall.