Multiple(quadruple) yolk eggs. Double-yolked eggs are reasonably common for ducks and chickens It is estimated that 1 in 1,000 eggs(out of 50 billion produced annually in the US) have double yolks. Eggs increase in size as the number of yolks increases. Far less common are multiple yolk eggs, including triples and quadruples, like the one pictured above. Apparently, the greatest number of yolks found in one egg was nine!