During my playthrough of Omega Ruby, there is this one Hex Maniac in Mt. Pyre. When you walk up to her, she says "No… you're not the one."
Which is the exact same thing that the ghost girl in Lumiose City says in X and Y. Are they the same person?
Here she is.
It is very likely they are due to all the similarites between the two.
But only gamefreak could tell you if your right or not here.