Thank you for the additional info.
How much did you reduce their light hours? How much light/dark hours did they have after reducing it? How long did you reduce the hours for? (i.e. how many days/weeks)
Increasing the amount of light can also discourage egg laying in hens. I have a hen that probably ended up being covered 24/7 because she was "too noisy", and she became a chronic egg layer. I brought her into my home, changed diet, change of environment, natural days and nights (in my area), and I've never had any issues with her and eggs.
I've never had to do this, but when separating a pair of birds, it is from my understanding that they need to be separated not only by site, but also from sound. In some pairs, it's enough to put them in separate cages right next to each other! That way, they can still see each other, talk, maybe even preen, but they can't mate.
Hopefully the pair is not intent on reproducing after this clutch, but if they are, you may need to take a bit more extreme measures to prevent future breeding until you are ready to allow them to reproduce again.