This is typical birthday paradox stuff right? The chance that these two photographers would ever snap the same thing at the same time is small, but the chance that any two photographers, anywhere, would do so is, I bet, pretty big (even if you factor in millisecond precision). With photographers being photographers and the internet being the internet, there's also a pretty decent change that they'd find out about it…
While technically the world is discrete in space and time (planck length), for all intents and purposes it is infinite in practice.
[1] yes, there is countably infinite, but that doesn't work with the pigeon hole problem.