Suppose a Fock state contains 2 photons, both in the same spacetime mode and having the save (vertical) polarization. So we can write this state as |2>, or, if we want to emphacize its vertical polarization, we may write |2v> or |2v,0h>. Suppose now we want to measure polarization in the circular (R,L) basis. If we had only a single photon, the question would be trivial. It would end up R or L polarized with the same probability 1/2. What happens when there are 2 photons? If each photon again makes an independent decision, then we will have 1/4 chance to find both photons R-polarized, 1/4 chance to find them both L-polarized, and a 1/2 chance to find them in different polarization states. In other words, we will get the analogue of Malus's law for the 2-photon case. Is this picture correct? And if yes, then how come the Fock state |2v> is NOT identical to the product state |1v>|1v>, when it behaves exactly the same way?