If all of your dupes die when you have a new dupe available then you can infinitely spawn dupes until you save and exit. once you reenter it stops the infinite spawn but as long as you don't save and exit you can get dupes. I paused my game when all my dupes died and I spawned 20 dupes before I pressed play. that was the first time. the second time I got 35 dupes. I wanted to let someone know because this could easily be the biggest exploit.
wait until you have a new dupe available then kill all of your existing dupes.