Just I on first level got a little bug where player was duplicated, first controls by me, second have sex with slime. 
this happened to me too, a double appears and then disappears after a few seconds. I managed to recreate it a few times by tapping the end button(space) at the same time as one of the start buttons(up/down arrows). it was inconsistent and only happened 5 times out of 13 though so idk if that is the cause or if there are other factors