Fleshchild/theories

Twin Theory
Under the assumption that Fleshchild's dreams have some origins from the stolen human brains, we can assume that the original brains are came from two conjoined children. Vice and Visi (as humans) were born conjoined twins and were separated, both still have memory of this. (Mutilation and conjoined effect)

As there is constant symbolism of their duality, we could assume that they were not only separated, but separated from themselves for most of their lives. It symbolizes their constant longing to be with eachother again as brother and sister. (Where the doll effect is found, both representations of the twins are next to each other, and could show that the both remember playing together.)

Perhaps both of the human twins requested to donate their organs, and their brains coincidentally ended up next to eachother in the lab.