I've wondered that myself. I'm pretty sure that my bottom hen gets the same 2 chicks. Strangely enough, I noticed my bottom hen was roosting high last night. All 12 chicks were huddled between my other 2 hens on the floor. Weird. Back to business as usual today though.
I've gotta post more recent pics of the older chicks. They're coming up to 10 weeks old for the oldest & biggest ones. Nice & meaty looking already! I'll try & get some pics of them up tomorrow.
Above is a pair of 6 1/2 week olds.
This is a pair of 10 week olds.
Here is my biggest cockerel at 10 weeks old.
Here you can see the size difference between my biggest 10 week old boy & my 6 1/2 week old boy on the left. I'll be using that big boy in my breeding program. He has great physical characteristics, although he has a yellow beak & legs. I'm breeding more for utility here, but will try to get the yellow out later. I will breed him to a couple of my big girls that have proper pale beak & legs.