I had a theory. Not a strong one, but a theory non of the less. "Danielle" was half ghost who looked like Phantom and half mortal who looked like Danny. And, if you can truest "Scarlett" then Phantoms named Danny before death. And Phantom appeared around the same time as "The Accident" and his death day was the same day. Like I say, my theory went against all logic and science but, here goes...
DANNY IS PHANTOM