As far as i can tell, it has only happened so far with two or more michael 4's. I haven't used two V4's in the same scene since the 3.1 update, but if i had to take a wild guess, it also probably happens with her. Maybe someone else can confirm that. I've seen no issue with the horde werewolf, sanctums alpha phenotype models, daz troll, and daz gorilla so far.