We have a WoJ that the reason Butter's Bob is so much like Harry's Bob is because Butters met Bob during that time and established a relationship with that personality. It might not have anything to do with having a name. (Or maybe it's a part of the latter). But I wouldn't attribute it automatically to a naming power of Harry's.
I'm not, i'm giving it to
giving a name, a name which is attributed to the self same thing by others as an identity, a mask.
If you really think about what the woj says.. Bob from Butters is directly effected by how Butters perceives Bob, by belief of
whom he perceived him to be.
I see strong indicators that Bob is nothing less than an immortal spirit(citation on immortal, inconclusive) tied to reality visa vi contract that defines his existence.... and the kicker is I can replace 'Bob is' with 'Mantles are' and still be on par with what I think. Bob is directly tied to whomever holds his skull last, is effected by them and vice versa, he uses it as his method of 'rent'. It's my belief Mantles do the same with the host directly, which is why the Sidhe whom are largely Mantles are more part of our reality than other immortals and those whom exist, like Hades, but whom have no right's to the mortal realm.