We shut our chickens in at night and let them out in the morning. These days we're very careful about always checking for eggs because the weather has been below freezing, and when eggs freeze they can crack.
This morning I let the birdies out and did my usual scan - nothing. When I got home in the afternoon I checked on them. Big Momma was in the process of laying, there was a blue egg in one box, a brown egg in another box, and another brown egg on the floor of the coop. I picked up the two brown eggs, and they were identical. They were the big, medium-brown eggs of our Rhode Island Red, Little Jerry Seinfeld. There is certainly no confusing her eggs with the others - hers are much bigger (though on a side note, yesterday I found a teeny tiny, M&M size egg that I swear was also hers...). I thought this was very odd, but decided that the one on the floor must have been buried in shavings this morning.
I went about my business in the garden and when I checked back to see if Big Momma was done yet, there were two more identical eggs in the corner of the coop on the floor! This is Turkey's usual spot and they were most definitely her colour eggs. They were near the same place where I found the other Jerry egg, and they were sitting right next to each other. One was warm, and one was not.
Of course that led me to the internet, which was MOST unhelpful in this area. A few people did what I did and exclaimed "My chicken laid 2 eggs in one day! What causes this?" And everyone else says "Do you mean a double-yolker?" or "That's not possible".
So I'm here to say, I don't know why it happened, but it is possible! The weather has been extremely strange lately, sunny to hailing to downpour to snowing all in one day. I wonder if this stress had something to do with it? Their diet has stayed the same and their routine has not changed.
I will continue my search for answers, and in the meantime, just know.... it IS possible for a hen to lay 2 eggs in one day!