gaken01,

I don't see why are you worrying. Make your 2 reservations and upon arrival tell the clerk that the 2nd reservation is yours and you want to stay in the same room. Or simply check-in to your (same) room next morning/afternoon. I don't understand your concerns, you are not breaking any rules, everything is legit.

I used points from different accounts on my stay in London. Checked in second time into the room I already had using 2nd reservation. It took me a minute.