Abnormalities
Three eggs frying, two of which are double-yolked eggs.Some hens
will lay double-yolked eggs as the result of unsynchronized
production cycles; although heredity causes some hens to have a
higher propensity to lay double-yolked eggs, these occur more
frequently as occasional abnormalities in young hens beginning to
lay. Usually a double-yolked egg will be longer and thinner than an
ordinary single-yolk egg. Double-yolked eggs only rarely, and even
then only with human intervention, lead to the successful
development of two embryos [1].
It is also possible for a young hen to produce an egg with no yolk
at all. Yolkless eggs are usually formed about a bit of tissue that
is sloughed off the ovary or oviduct. This tissue stimulates the
secreting glands of the oviduct and a yolkless egg results.
from wikipedia came across this a few days ago lol
