DigDugs And Jaws seeds are clearly conjoined seeds that grew together into a double seed. Normally we sort seeds like those out because they look abnormal. They are always two.
Often you can even break those double seeds in half and have two viable seeds.
Rapid evolution (AKA contemporary evolution) can take place in just a few hundred generations under natural conditions. Inbreeding can increase the rate of mutations significantly.
Contemporary evolution is evolution. Find me a single evolutionary biologist who disagrees with me.
There are studies which show that there is a genetic basis for fraternal twins. This means that is is possible for mutations to arise from inbreeding which increase the likelihood of twins being born. I'm not saying twins themselves are a mutation, but you can have mutations which increase the rate of twins in a given population.
The real question for me is whether there are 4 gametes involved as is normally the case with 2 seeds. If less than 4 than they are more "twin' than any two others seeds from separate calyxes (doesn't make them any more stable for breeding though).
Anyway, here's my recent double yolker, which is from a normal round seed, third this year (out of roughly 150 seeds). Just a small plastic cookie box with coco so was easy to look for shell, definitely came from a single seed.
I have one growing like this and one growing 2 seperate plants. Can they be both make and female? Since it's a cross I made can one side favor the mom and they other side favor the dad? The cross pictured is sleestack x kandy kush and the other not pictured is SoCal master kush/c 99 x kandy kush. I'm assuming the kandy kush male is causing the twins.