No problem, they arn't too tender in this stage so I can dig one up again.

The radical is the first and primary root.

Can you have two “firsts?”

I have some Q. Robur and Q. Lobata which sended up 2 shoots from the same acorn. I just snapped the one that seemed to be weaker and let the stronger grow.

Maybe it isn't so rare anyway. But are there two nuts inside each of those acorns, or is it one nut with two radicles and one shoot on each?

You have twins, two seeds in one nut. It happens in chestnuts too, as well as oaks:) Citrus is even worse, grin.

looks like a yellow kermit with his head stuck in an acorn ...

4 cotyledons, two embryos, all in one shell. When the little trees get woody, you can peel away some of the shell and gently pull the intertwined cotyledons apart and plant the two separately if you want. Wait till they are woody, then they don't mind if you peel away the shell.

I think I will just cut the weaker of them to not risk both of them. After all, I don't know how many more red oaks I need, they are pretty large growing