say you had 3 lookalikes out, could you KO supes, put a character named supes into your front row and then do the same thing with the next plot twist, so as to get 3 supes out for each time he gets stunned?

no, Look alike Squad is a triggered effect that has a cost. the trigger "Whenever a character you control named Superman becomes stunned" and the cost, "you may KO it" and an effect "If you do, you may put a character card named Superman with cost lower than the cost of the KO'd character from your hand into your front row.
"
you must KO the Superman that had became stunned to put out a new Supes. you cannot KO the Superman more than once, so you cannot put more than one Supes out per stun

EDITED for acctual card text and clairity

thanx, thats what I thought, people have been chaining lots of stun-remove from game-bounceback science spire villens united stuff, and I wasnt sure.