I don't think it's at all clear. If someone comes up with evidence saying it's not them (or one of them) we'll remove it. For now, I believe it's speculation.
I'm just saying that I searched the picture, and the only matches on Google are from a random girl's tumblr from back in 2011 and not anything to do with Selena or Vanessa. So in actuality, saying it IS them is pure speculation. Picture link removed, thread locked I'm now convinced that neither of the girls in the pic are Selena or Vanessa.