You don't get identical results, because the `object` version uses only one random generator sequence to generate all the photons, whereas the `config` version uses a number of differently seeded random number generators, one for each image.

So, over the last couple of days I've been talking with a colleague (Sree Balan, who wrote the G08/G10 code) about how we currently do the random number generation, and he has got me spooked about it once again.  He's on github so I think I might open an issue to have the discussion there and get him involved: he's sent me a bit of material about what we might do instead of using lots of differently seeded generators...

In summary, the problem that Sree raises is that RNGs generally only guarantee that their numbers act like IID RVs from a single sequence, they don't guarantee much about how the sequence is initialized from their seeds.  By seeding using consecutive seeds as we do we might in fact be getting a whole load of numbers from similar locations in the overall sequence, and so our results will be statistically correlated.  As we can't guarantee that different seeds in the same RNG produce statistically uncorrelated RVs, only that a single RNG approximates an IID sequence, there are maybe reasons to be worried... I'll open an issue for the discussion, it would also be good to get Gary in on this as well as Sree.

Anyway, part of the point of the object and config functions was to test consistency of results due to my ongoing nervousness.  This deserves at least a comment as you point out...!