Hey there M1sty. I can assure you that to the best of my knowledge the enemies do not spontaneously respawn on top of the player lol. That would be a very interesting game design or a very serious bug that I've missed.
( I am not sure which part of the video you are referring to though. )
It was this video. Around 1:35.
Ah yes! That was a bug for the enemies to respawn if they moved a certain distance from player. I think I fixed it. Or will be fixed in the future (have to sort out the pipeline of game productions, currently focused on Little Lost Robots' full release).
It happens very rarely though and hopefully won't ruin the experience. Thanks for showing me where you saw it!