quantum gravity - Can two observers on different components of the wave function, interact gravitationally?

In a semiclassical gravity theory, the Einstein tensor is proportional to the expected value of the energy-momentum operator on a state.

Now if the state is a combination of two eigenstates, each one contains an "observer", can they detect the existence of the other by measuring the Einstein tensor? Is there an experiment or an argument to forbid this?

Say, if I setup a Cavendish-type experiment where the configuration depends on the answer of a quantum random number generator. Then the whole experiment will be in a superposition as being observed by people from the outside. The question is, should we expect a deviation from the classical gravity theory be observed?