Interesting question and not fully answered by the rules. But, the rules do say "after 5 pm CT on May 15, no medical school in Texas may offer a position to an applicant already accepted by another medical school in Texas", now, I would interpret this as meaning that "already accepted" refers to the applicant formally accepting the offer. From the time they make the offer, they will give you 2-5 days to accept, depending on when it is relative to the school start date. However, the second school might not see the first offer or acceptance on the TMSAS website (remember, no CTE in Texas) for a couple of days after you accept it and could offer you a place without meaning to violate this guidance. So, I think there would be a bit of flexibility for a few days around this. I do think that once you had accepted the first offer and it appeared on the TMDSAS site that the second school would not make an offer, excluding exceptional circumstances. I also think you COULD call school number 2 after you get offer #1 before accepting it and see what they say. Not sure what they'd do but I don't think it would be a terrible thing to do if you really preferred school #2.