[Homura7]

Spoiler for spoiler:

Nah, the real Arca is the one we already know, same goes for Teruyama. Don't break your head, because what you say is inconsistent with their characters.

But one thing is clear, the real Teru is what we just saw at the end of this latest chapter. And yeah, he's dead and his remains preserved in order to bring him back to life through Simeon's advanced technology. As for the one in Needless Zero, is most likely him without his memories messed up.