And there is another big problem with the doppelganger theory in that if you play as a warlock you will see your patron, if you are a paladin you can break you oath...those things could not happen to a doppelganger because a doppelganger would only mimic a warlock, it would not actually have a pact with a patron. A doppelganger would only mimic a Paladin, it would not have any oath that it would need to uphold or that it could break.
