What generally happens is that as the egg is developing and being pushed down the oviduct, a series of abnormal contractions can occur which can push a developing egg back up the oviduct. What happens is that one egg will be surrounded by another egg.
What’s less clear, in our research, is whether you could actually eat this double-shelled monster. Double-yolk eggs are comparatively more common and are safe to eat. But in all the news reports we’ve come across of double eggs, nobody has seemed willing to chow down on one. As Texas farmer Cookie Smith said to the Abilene Reporter-News after her chickens laid a double egg:
"No way. It may be fine, but it’s a mutant egg," [Smith] said. "Its DNA may be messed up or something."
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