Main Question or Discussion Point
What happens if two blackholes of identical mass collide, but one is anti-matter and the other is regular matter? Would all of the matter anihilate in a gigantic explosion of photons which could be detected by a far away observer? Or, would all of the radiation energy, which would still have an enormous gravitational field equal to the combined energy of the two original blackholes, remain trapped within the event-horizon of the now, merged, single blackhole? This would be like a black hole made of nothing but photon energy (which I am assuming still warps space-time).