I personally don't see it that way.
To me, here "Dorothee" have to play the "bad guy"'s role for this Elsa to be more confident in herself which is the main reason the curse manifested so strongly. Even if what she said about Elsa being a fragment of herself , I don't think her goal is to take...
Are we really going to forget that Elsa took into her the "Sage's curse" from the Half-demon girl (sorry I don't remember her name) ? It has to come back sometimes later, its the whole reason she shouldn't use too much of her own power in order to keep it down.