So... I was busy putting builders on the rock that was being chisled and there was a group of kiddies dancing near by when a mushroom popped up right there!

I "forgot" to put the game on PAUSE to get multiple mushrooms, and just started picking kids and putting them on the 'shroom. Imagine my surprise when four kids all managed to pick the same 'shroom! Repeat, this was not in PAUSE mode!

So multiple mushrooms are possible (without "cheating") you just need to be very lucky and fast to do so!