Interesting. I never or almost never had a double-yolked egg from a standard grocery store carton back when I used to buy those; but fairly often get them from small-farm eggs, whether organically raised or not.
I’ve assumed this is because small farms are more likely to keep older chickens, who produce larger eggs; and the larger eggs are more likely to have double yolks, though I did get a double yolk in a not very large small-farm egg just the other day. I might be wrong; I don’t myself raise chickens.
I usually buy large or extra large; though sometimes the eggs I get aren’t size-sorted, or large ones aren’t available from a source that I’m willing to buy from that’s also easy to get to that day.