It is my limited understanding that the idea of "a different photon" would be sort of irrelevant here as quantum state is the only thing that differentiates objects such as photons from one another. Outside of that, photons are essentially fungible. I don't really understand the finer points of the experiment however and I could be totally wrong in my understanding.
Oh yeah, I think the current model is that it gets stuck in an electron somehow. But since it preserves the quantum state, it's still usable for quantum crypto and quantum computing.
