Serious Eats - seriouseats.com

When I was young and impoverished I used to work in an egg packing factory, a horrible job, but it paid well. As people like their eggs uniform my job was to check that the eggs were all the same - they would pass in front of me on a metal grid and a bright light was shone through the eggshells.
Any non-uniform eggs - double yolkers, part fertilised, deformed shells, that sort of thing, were snatched from the line and thrown into a big vat, and taken off to be dried to make egg powder and used in cake manufacturing

Could the egg checker in this case have meant to put the double yolkers on one side for disposal, but made a mistake and packed them instead?