TSC mixes them up the worst 

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I live in the UK and have never travelled across "the pond", but from reading posts here on BYC even I know that TSC are renowned for mixing chicks up and selling them misidentified.
As someone else said, anything with a red comb at this age will almost certainly be a male so you have quite a few cuckoo marans cockerels. The lighter colouring is usually a good indication of them being male too, so next time you go shopping for them, pick out the darkest ones and probably safer to buy from somewhere other than TSC if you want a specific breed or sex.
I doubt she was lied to. I bought 5 Buff Orpingtons, 2 days old, as pullets from Southern States co-op. One turned out to be a beautiful rooster, which didn't bother me a bit...he's taken good care of his girls when they're running around the property. Hatcheries aren't infallible; they make mistakes.In your pics I'm seeing mostly cockerels.
I wonder if they were actually sexed as cockerels and they lied to you...
Feed stores, I suspect, label their chicks according to what the supplying hatchery tells them. First flock I bought were supposed to be RIR; turned out to be RSL. Great layers; just misrepresented.x2. These are hatchery cuckoo Marans, and the males are lighter colored with bigger and redder combs. You have 'straight run' chicks; some cockerels, and some pullets. Plan to keep only one cockerel, if any, and move the others on. They will be tasty!
Feed stores are notorious for mislabeling their chicks, which can be very aggravating.
I have no experience with Atwood's. Is it a feed store? Hatchery?
Good luck with your birds, they look very nice.
Mary
From what I've read, the French Marans has feathered legs; American is clean-legged.French Marans have some feathering on their legs, will lay darker eggs, and are available through some hatcheries, and for show quality, from private show breeders.
I have some from Cackle hatchery, and like them very much.
Mary
TSC's been known to sell turkey poults as chicks.Atwoods is another store just like tractor supply. That was where i got the darker birds that were older and all banned as being sexed females/ pullets.
Tractor supplies were not banned just in bin that said pullets and employees said pullets
Honestly i find Dominique, barred rock and these Marans look so similar but was wanting the darker brown eggs. Not the darkest just darker than tan is fine
Some of them don't know squat about what they have. I stopped in there a week or so ago for a bale of shavings. Girl said they were out of one kind. I wasn't sure what my kind was called, so I had to go out with her, show her where they were, & verify that what they had was what I needed. I swear some of them wake up in a brand new world every morning; kinda scary.yea, that was a good one!