Morning all 
So I have done a little research last nights and there’s not a lot on this matter seems twins propping from a seed is quite common but to have a Siamese twin Is quite a rare occurrence twin seedling can be split at birth growing two tap roots where as Siamese twin have on root one stem and two heads There has been a few reported incidents but no much information on the matter but from what I read it’s a genetic mutation as the embryos grow there’s squeezed and form into one Siamese twin very cool 
@Wishbone believe you had something similar going on with your amnesia haze