In Emergencies/Diseases, etc. you will find this helpful post from KimClain:
I just HAD to go out and do some research on this... I'm finding many mentions of hens laying two eggs per day. Here is the best site I've found...refer to page 8. It IS possible to have two eggs per day...
Did anyone's chickens who were laying multiple eggs per day survive? Or did they all get egg peritonitis and die? How long did they live after the daily multiple-egg laying started or occurred?
Thanks for your help.
Clare