you should add a way to save both people and a reaction to doing so, even if you do not think it possible.
that is, a room which could fit two people, such that the goal which does not end the level can be stood on when the goal which ends the level is stepped onto.
then if you wish, you could add some lore reason for why only one of the people will be proceeding to the next chamber.
I think chamber10 is the only one for which this is possible. most of the levels after this are too restrictive, and ones before don't have enough boxes to hold down a button on the other side of water/pit, so the button to unlock door+no box rule is enough to prove imposibility.
chamber 10 just happens to be the only chamber in which there is nothing strictly blocking the door when nothing is active
