I think I'd accept the offer I like best and shred the other one. It never happened.
Sorry, Mike, but absolutely not! If the other offer turns out to be the correct one and mashk fails to accept it, the child could be left without a school place.
mashk, I would endeavour to get written
confirmation from Admissions and/or the schools as to which is the correct offer. If that is not provided with absolute certainty before the deadline then I think you should do as you have suggested - accept both offers and hold on to them until it is completely sorted out.
It would obviously be unfortunate if that means another child has to wait longer for their own place, but you have to look after your own interests first.