Oh I like that! A secret reward for players who manage to get both out. I’ll think about how to make it work and secretly add it. Thanks for the suggestion :)
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