It’s a genetic trait, so if they kept breeding a twin-maker hen for efficiency alone (if you raise chicks, you get 2 for 1 effectively), that could mean that most of their stock are now laying dual yolks.
The two yolks together are like 30-50% larger than one regular one, so the nutrition facts are slightly changed since the amount of egg white is reduced.
Since most calories actually come from the yolk, I’d say it should be noticeable to some degree, if you really measure it.
(This answer was brought to you by my wife, who happens to be a nutritionist).
They do sell double-yolkers as a thing. You can shine a light through the shell to identify them, apparently. Higher value product so producers who get enough of them will go to the extra trouble of sorting them.
Yeah I’ve only bought them once and it was unintentional. Living in a place where I didn’t fully grasp thr language, I thought I was having the luckiest egg day ever until I translated the carton!
