SO rose just got her own version of davesprite, Given Terezi's body is also on Johns Planet, could there possibly be two terezis (Terezai plural?) at some point.

If somone prototypes her then yes there could be two Terezis. 

Edit: Terezi’s body is on Lopan not Lowas and John only brought Lowas with him so no Terezi cannot be prototyped.