Let's say player A has this card in play. Both player A and player B have a hex token in front of them. Player A would like to use NMH to take a card from player B to play on his hex, but player B would like use that same card (his only card) to play on HIS hex in front of them. Given that cards on hexes need to be played simultaneously, how would this resolve?
Would the situation change if player B had more than one card in his hand?
Unlike Whirling Nightmare, which can be used with No Man's Hand to discard someone else's entire hand, No Man's Hand itself is not intended to deprive another player of a card for a round, but provide an ever-full hand to the No Man's Hand player (assuming they pull legal cards).
The official answer is, player A and B may play the same card in a turn, but I understand the grey area presented by simultaneous play.