We get an occasional double yolker from our isa browns hens; I’m presuming it is the same hen that lays these.  They’ve been dubbed the “Mega Egg” as they are massive compared to the slight size of the hen that lays it.  Here is a photo of the latest Mega Egg compared to an egg from our silkie hen:

We’ve started weighing the mega eggs.  This one is 106g.  Ouch.