Laying double yolk eggs, although nice for us, is bad for the hens. Many of todays hens are bred for laying huge eggs every day, and that can lead to several different reproductive problems, such as impacted oviduct, salpingitis, internal laying, and egg yolk peritonitis. Some of these can be sterile or caused by bacteria. E.coli, mycoplasma, pasteurella, and salmonella are some of the possible bacteria that may cause salpingitis and EYP. Very few antibiotics treat E.coli successfully, but Baytril can. Here is some reading about some of the conditions:
https://thepoultrysite.com/disease-guide/salpingitis
https://the-chicken-chick.com/salpingitis-lash-eggs-in-backyard/
http://www.poultrydvm.com/condition/oviduct-impaction
https://thepoultrysite.com/disease-guide/salpingitis
https://the-chicken-chick.com/salpingitis-lash-eggs-in-backyard/
http://www.poultrydvm.com/condition/oviduct-impaction