How did the double yellow goose eggs come from?

Double yellow eggs often come from hens who have just started laying eggs in adulthood.

Double yellow eggs are formed because two eggs mature at the same time and are separated from follicles and brought into fallopian tube, where they are wrapped by protein, shell membrane and eggshell in turn.

Sometimes even multiple eggs mature at the same time and are brought into the fallopian tube together, thus becoming multi-yellow eggs.