In my country, there is an opinion that two-yolk eggs are obtained when chickens somehow change the light regime. I got such eggs in late autumn and early winter, when the dawn here is very late (11 AM) and the sunset is early (16 or 17 PM), In addition, they have a molt at this time and for some time they stop rushing at all.Youngest have been laying since last yr. The big egg came from hens that have been laying for 3 yr now. Recently they have been laying those large double yolkers. The chicken egg next to it is a normal sized one.
Leghorns and their crosses are quite popular here, as I understand they are half Italian breed and are used to a long, warm day, but here in autumn and winter it is completely dark, so they, especially if I stupidly turn on/off the light (I was somehow too lazy to make light sensors or enter lighting through hourly timers) Chickens sometimes produce two-yolk eggs.
The fact is that my daily routine is completely messed up, before my work meant night shifts, then day shifts, as a result, even when I quit my job and began to live unemployed, I sleep at random - then I sleep during the day, then at night, and, accordingly, then I turn on the light for chickens in winter, then I forget to turn it on ))
At one time, the goats really did not like these habits of mine - at exactly 4 AM, they began to bleat and demand that I take them home. But then, especially when they lived with me for several years and gave birth to a bunch of other goats, these animals got used to and began to lead the same frivolous lifestyle - we either sleep during the day, or walk through the forest in the middle of the night, eating nettles, and jump out onto the road, scaring the belated summer residents returning on foot from work from the bus.
Over time, the truth and summer residents got used to the fact that in the middle of the night a herd could pass through the village. There are no predatory animals larger than a fox in the forest, which is why we often walk at night. And sometimes I take the herd out during the day, and I myself lie down and sleep on the grass while they graze nearby.