The setting I'm building has a race of people, derived from modern humans, whose primitive survival as a species relies partly on very fast reproduction, and I think I want them to have a tendency for litters instead of being prone to one infant being born at a time.
I'm not satisfied with the similar threads On the Encouragement of Twins to be Born or Increasing the Rate of Multiple Births in Humanoids? or How can I Determine the Litter Size of a Species? because they're all about the evolutionary causes of races having litters. I'm just going to grant that there is an evolutionary problem, but I want to know if the solutions proposed would work.
I don't want to take the easy route and give this race more pairs of ovaries, so I have a couple suggestions and want to know how plausible the scenario is.
1: Simultaneous Ovulation
In this scenario, the females of this race would consistently release eggs from both ovaries at once, which would roughly double the chances of successful conception when in heat, and drastically increase the likelihood of twins. I'm pretty confident this would work, but I'd also like to hear your thoughts on point 2.
2: More Identical Siblings
In this scenario, something about the race's biochemistry causes post-fertilization cell division to be very common, meaning that any given fertilized egg is much more likely to develop into identical twins, triplets, etc. I think this would be very interesting to see but I'd like to know if it could happen. Is there any known phenomenon that causes identical siblings to be more common?