I briefly considered the possibility of this Bella being a Volturi impersonator too, but I didn't delve into that hypothesis as much as the others - probably because I don't really like how the Volturi has all these original characters with awesome gifts. It definitely makes sense to send Del if they have an agent with a gift capable of impersonation though. It would be another great move by the Volturi, even though this situation and the one in La Push more or less fell in their laps, and they just proceeded to do the obvious with what they had. Playing on Cody's loneliness was a smart move though, if that is what they did.

I think I'll be disappointed if your hypothesis turns out to be true. I think the only thing that even slightly speaks against it is that Bella's/Del's eyes turned black when Pera hid her. I don't know if Del would react that way, but Bella certainly would if Pera is her singer. I can't wait for tomorrow's update!