Cockerels or Hens?

I was fortunate to be given 20 fertilized eggs from a friend who has registered Show chicken champion Rhode Island Reds. 12 chicks hatched and all have survived & are now 12 weeks old. I can definitely peg 8 of them as hens - small yellowish combs, tiny to non-existent wattles, docile behavior etc. However of the remaining 4, I am confused !!! Two are large birds, prominent reddish combs, shiny looking feathers and starting to develop greenish hackle feathers. No real indication of wispy saddle feathers but just look like roosters. The issue is with the other two - both brownish, no really shiny plumage, yellow - pinkish combs & the one has its juvenile feathers still on its head. I recently enlarged their run by a further 6 sq feet. The two youngish "roosters" are now chest bumping, puffing out their neck feathers & acting all Kung-fu Panda pants. They only take issue with each other & the two large "roosters" simply ignore them. So my question is - Could these two just be hens having a bad feather day or do I now have two confirmed roosters? The two large "roosters are now acting even more docile than ever.

We are going to need pictures to help you out. You will need a few more posts before you can load pictures though. Here is a thread all about non-hatchery Rhode Island Reds you many want to look over. Great pictures of some very nice birds there.

https://www.backyardchickens.com/t/407294/the-heritage-rhode-island-red-site/8840

Oh, and there is no "chicken registry" for show birds.

i have RIR and as in most of the breeds i raise the roos always have short tail and wing feathers after about 4 weeks is good time ....the hens longer tail and wing feathers. it has always applied with the ones i raise......jeff

Thanks. I will post a few pics when I am allowed to Their behaviour has settled down, so maybe it was just a pecking order issue.

Thanks Jeff, I "woke up" to the sexing issue a little too late. Maybe next time I'll do the wing feather check at 3 days & then keep an eye on them at 4 weeks. If you have any pics of what to look for I'd appreciate them