Double yoke what about a double shell

[Sissy]

My cochin layed a double hard shell
it cracked in the bator and there was another
shell it cracked but all goo in side.
.. was I seeing right.
all that was there was a double layer of shell
why did this happend.anyone have an answer..
could it be too much calicum??
they are raised on purina laylena.
and a few veggis once in a while
and yogurt and milk no fat.once a month.

 

[Cats Critters]

I've heard of it happening, from my understanding it was just a mess up when she layed her egg, like when you get double yolkers.