I can’t find anything in the rules that prohibits placing two ubertubes on one scoring peg during autonomous. Sure, it would be tricky, but it could be done.
How would they be scored? Would they each get normal points, or would one double the other, or would both double the score of the other one?
Also, let’s say one of them pops, and a third tube can fit on during teleoperated. Does it earn quadruple points? Just something to think about.