Contact the school that is delaying the FA and ask if they are extending your offer past May 1st, get it in writing and then deposit at other school. If the school that gave you the extension comes back with an offer you want then put down deposit there and notify the other school you are withdrawing…and losing your deposit.
Not sure where the OP is from but I think that final transcripts, at least in my neck of the woods, don’t get sent until late June/early July due to school not finishing up until late June. I guess that depends on where you are from…I think southern schools are done late May/early June?
That said, if you double deposit and they find out they can rescind the offer. Not sure how they would find out in early/mid May but if your school doesn’t send the final transcript until summer then I guess you roll the dice if you double deposit and by the time you request which school to send the final transcript to you are only sending to one.
Agree that the one that won’t give you the information until after May 1st is odd.