  We show that the possibility of distinguishing between single and two photon
detection events, usually not met in the actual experiments, is not a necessary
requirement for the proof that the experiments of Alley and Shih [Phys. Rev.
Lett. 61, 2921 (1988)], and Ou and Mandel [Phys. Rev. Lett. 61, 50 (1988)], are
modulo fair sampling assumption, valid tests of local realism. We also give the
critical parameters for the experiments to be unconditional tests of local
realism, and show that some other interesting phenomena (involving bosonic type
particle indistinguishability) can be observed during such tests.
