Anyways, onto the 2 miller claims. I think we're going to need some more information on this to decide if its legit or not.
Theme wise, multiple millers in Jojo wouldn't really be unheard of, its rare to have so many in a game, but again theme wise, since people get shit kicked by the protags and tend to become temp allies in the end so again, not exactly something to discount. Not sure who's more believable or if we want to push for more information but right there isn't any overall hint. It can help us narrow down suspects though as well in the long run.