Well, the first time we saw him, he was hiding among high class humans, a characteristic that heīs known for, he likes mingle with them, living a human life.
But he wasn't like this the last time we saw him. I guess it could be his new, er, "private" face... or something... It doesn't seem like this is the only Tyki that exists now.
Whatīs different here itīs his "awakened" Noah form, which is something alien to him now,
Either that or there are two Tykiīs like you said, although i donīt find it likely.
The dream greatly resembles Lenalleīs "premonition dream" which had at least some paranormal source to it, it could go either way really, the 14th is either taking a semi proactive role in the possession of Allenīs body or he takes a plunge everytime Allenīs subconscious makes him vulnerable or unaware of the whole "Mana could be using you all along" because regardless of whatīs exactly happening Allen was possessed for a few seconds there.
Is that the 14th acting, though? It could be that the 14th isn't actually an active spirit, but the result of whatever Allen does. It's not as if Allen's dream wouldn't entirely be due to his own insecurities. He remembers the level 4's comment on his sword, for instance. It could have been the 14th playing to Allen's insecurities about that and Mana... but it could also be Allen's subconscious.
He could might as well mimic other voices as far as we know, why would his innocence talk to him in such an peculiar manner?
Also, the voice Allen hears seems far more likely to be either Innocence or himself than the 14th (well, for one, the 14th speaks entirely in katakana, so it's pretty much proof that wasn't him talking - you'd have had to know the raw for that, though).