According to photon theory of light increase in intensity means increase in photons but intensity is energy per unit area per unit time then why do we say intensity and not photon flux because photon flux is number of photons per unit area?

since wave theory and mechanical theory are not related to each other.

according to wave theory intensity determines the amplitude of the wave but in case of intensity in mechanical theory it explains about the work done per unit time per unit area. As their dimensional formulae is same but their properties differ in above manner. Hence we cant say that they both have same properties