X2, what Veer67 said.
For a while some hens I had from different mongrel parentages were laying doubleyolkers and I culled that out quick smart once I saw what it was costing the hens to lay those eggs.
If it happens too often it is a massive strain on the hens and is more likely to kill them than a normal egg for obvious reasons. It is genetic, hence the culling.
For a while, decades ago, people tried to develop doubleyolker egg layers as a breed, but it failed due to the dangerousness of the trait to the hen's health. As a general rule it is a genetic trait that is culled out, not encouraged.
It's like the initial popularity of breeding sheep that give birth to monstrous lambs for the lamb meat market. It is now an unpopular genetic trait due to how often the ewes die or need assistance birthing these oversize babies. Also, the babies are weaker, slower, and needier, altogether more prone to die than smaller, fitter, faster babies. With doubleyolkers, the very few chicks that have been hatched from such eggs are weak and do not tend to make it to adulthood. I hatched a few before giving it up as a fool's errand.
It's a negative trait, as promising as it may seem when you first see huge eggs with double yolks.
Better the hen who lives many years producing steadily than the hen who lives a year producing excessively and then dies worn out. If she is producing within her capacities, her product is superior than if she's always overproducing due to genetic inclination.
Best wishes.
