What I read, their reproductive system is not quite ready to go yet and they produce odd eggs for a bit. I have had egg "farts" too. Very small eggs with no yolk at all.
It is very weird that you got an entire box of double yolks. I am guessing what someone else said, that they got pulled out and then accidentally sold.
I keep my own backyard flock, and it is much more expensive than buying store eggs when you account for the coop, food and medical costs. If you have access to building sites, it is possible to build a very nice coop from salvage, but it is some work too. Most people purchase something. Feed is expensive. My girls free range and get table scraps, but the bulk of their diet is pellets, especially in the heavy laying season. Medical costs. One of my girls got a scratched eyeball and I purchased ointment to treat it that was in the $30 range plus my time. How many cartons of commercial eggs can you get for $30? From a cost efficiency standpoint, it would have been smarter to let her suffer and maybe lose the eye. In a commercial operation, the injury would not have even been noted. If she got too sick, she would have been culled. So it all adds up.
I also do not cull. Chickens lay heavily for the first 2-3 years. After that they tend to slow down. Professional operations cull the older birds. To be honest, many small farms do too. But I do not. Everyone gets a meal ticket, even if they are not the most productive layer around.
On the plus side, the eggs from my backyard are much nicer than store eggs. Free range chickens eat weeds and bugs and get plenty of sunshine and fresh air, so the yolks are a bright golden color. Compare it to the anemic pastel yellow of store eggs. And there is likely less cruelty involved with smaller flocks. Mine is part of the family and our own tiny ecosystem.
So it is probably worth the small extra cost. Yanno, you could always get your own small flock. Chickens are surprisingly nice pets, in addition to being a great asset to the kitchen
Another hint, if you want to hard boil your local eggs, keep a dozen at the back of the fridge for a few weeks. Local eggs tend to be very fresh, and fresh eggs are hell to peel. I have had a few very unhappy deviled egg making sessions using too fresh eggs where the shells would not separate from the whites.