Help! Two reservations with ADR's coming up.

[Sommermo]

I am currently double booked on purpose and still unsure which reservation I will keep (depending on flights and vacation time) One reservation starts on 11/24 and one starts on 11/27 both ending on 12/2. My ADR's will open on 5/28 for the longer stay. So I am assuming that I can book through 12/2 on 5/28 and then just cancel what I don't need if I end up going with the shorter stay. Am I correct? Will I encounter any problems on 5/28 since I have two reservations?