Why does this entire carton of eggs have 2 yolks each?
Double yolking tends to happen more often in spring and with young or very old birds.  As commercial egg producers do not tend to let their birds get old, unless you are getting farm eggs, they are likely young birds.

Automatic candles may be set up to separate these as suspect so they had to be re-run to verify they were not bad, which will result in them being grouped.

When I raised birds, it seemed like brown egg varieties have this occur more often than white eggs, but that is just my experience.  Some people actually try to breed for this and it is more common in some birds.  It also makes young birds a bit more profitable as the eggs are large than they would normally be for new layers.  There are considerable downsides as well for the birds though.  The eggs are not viable, almost always if incubated the egg will fail as if both are fertile, the egg cannot support twins, and one failing in the shell will lead to the demise of the other.  Also, the eggs are larger, so a young bird is laying eggs larger than it is physically ready to lay, and for an old bird the eggs can become monstrous.  This causes a much higher mortality rate in birds.

I have very seldom had double yolks in commercial eggs, but there seems to be something in the water this year.  Just last week I had a dozen also that 10 of the 12 were double.  Just my luck, I was trying to make angel food cake and did not want them.  lol