Relativity requires that all inertial rest frames are exchangeable. As seen from one speeding photon, another photon will still appear to be travelling at the speed of light, even if it is travelling in the exact opposite direction.

This raises some interesting questions of how an observer travelling with the first packet of photons would measure the progress of the second packet. For instance, he might look for reflections from interstellar dust to occur as "echoes" of the light travelling away (just as we, based on Earth, can see light echoes from behind supernovae).

Aha, you ask! How can one packet of reflected photons EVER catch another packet of original photons - well, they can't in our rest frame, but if you WERE travelling at the speed of light, you would experience infinite contraction of time and one packet of photons WOULD catch another after a finite time, measured in that rest frame.

A real head spinner!

(alternatively, you might posit a Newtonian, Euclidian universe, but we know that that conceptualisation breaks down as v/c>>1)