Yes. Energy will be conserved but where and when that energy turns up will depend on the situation.When considering photons, 1 photon+1 photon=2 photons, but their electric fields don't add in a similar manner.
That equation looks pretty much like a standard diffraction / interference formula with some extra jiggery pokery. I still have a problem with actually assigning phase and position to the photon and that equation seems to be doing that. (from a fuzzy inspection)