After my wife told me that a few of the eggs she was going to eat had double yolks, she refused to eat the remaining eggs. So I took it upon myself to really test these eggs, plus we had purchased two-dozen of these Kimbo Grade A Jumbo eggs from the 99 Ranch Market. I believe Kimbo is 99 Ranch's house brand. Which is starting to explain a lot. Check out this video to see my test of cracking open 10 eggs open.
I did some further research on the phenomenon of twin eggs, and it turns out that it is quite common in jumbo-sized eggs. By the sorting process, the eggs are sorted by size, and all the jumbo ones are put into jumbo carton, the similarity in size keeps the eggs from getting crushed in the carton by more evenly distributing the weight. But you don't car about the carton, you care about the yolk.
According to a website called www.countryhen.com, "Hens begin their laying process with small eggs, then medium, and eventually over the course of time are laying large, then extra large and finally jumbo eggs before they stop laying altogether. It is the jumbo eggs that have double and sometimes even triple yolks. The number of yolks reflect only on the age of the hen, not on the feed they eat or any other factor. The egg with a double yolk is still fresh and Grade A."
I consulted another website called PoultryHelp.com which stated, "Double yolks are a 'mistake' in the chicken's reproductive system that sometimes happens when a hen just starts laying eggs and her system is still trying to figure out how to do it correctly." The site goes on to say, "Double Yolkers appear when ovulation occurs too rapidly, or when one yolk somehow gets "lost" and is joined by the next yolk. Double yolkers may be by a pullet whose productive cycle is not yet well synchronized. They're occasionally laid by a heavy-breed hen, often as an inherited trait." PoultryHelp.com has an illustrative list of other egg oddities that is worth a read.
So after throwing ten eggs down the drain, it would seem that this string of twins is not too abnormal, but I still cringe a bit when you consider what hormones may or may not be pumped into the hens to make them crank out eggs faster. Much like women who go through fertility treatments are more prone to having multiples after getting pumped full of who knows what, that may be what is happening to these hens. So I'm still weary of eating these, and I think I'll stick with medium or large eggs purchased from more reputable markets.
I Pity The Hens.