Consider two simultaneous matches in which a GM plays against Players A and B, constrained by the rule that the GM must make identical board moves in both games. Players A and B can play as usual.
Thus, for example, if Player A takes one of the GM's pawns, but Player B does not, then the GM forever loses the ability to move that pawn on Player B's board as well.
The GM only wins by winning against both Players. We can also stipulate two versions, in one of which Players A and B can cooperate, and in the other of which they cannot.
Question: Could two average Players A and B always win against the GM in this setup? Would it matter if they are allowed to cooperate or not?
(I'm not necessarily looking for a mathematical demonstration of the answer, though if there is a simple winning strategy, that would be nice. I would be glad to hear from good players about what they think would happen.)