That's breeding posture; I've never seen newts fight, but I feel certain they don't do it by trying to amplex their opponent.

Was the eastern wrapping its legs around the Chinese newt's neck? That's the normal posture. You may also have noticed the male rubbing its snout and cheeks on the other newt; this is done to transfer pheromones.

I very much doubt you'll get any viable young from this; the eastern is just randy. I wouldn't separate them unless the other newts seem stressed.