An unfertilized egg isn’t anything like a baby. That’s like saying every woman culls her children every month on her period (the mammalian equivalent of laying an unfertilized egg.)
That being said most reptiles will actually break down their unfertilized eggs internally to be uptaken by their bodies once more. Regular egg laying of unfertilized eggs is something that’s been bred for in domesticated animals. In the wild it represents a distinct evolutionary disadvantage since you are wasting energy for nothing.
Overall I don’t really think this sort of idea is remotely necessary. Slime already has a form of parthenogenesis and I feel like without good reason the other mutation categories shouldn’t really step on one of Slime’s main bonuses, given all the disadvantages in the Slime tree compared to others.