ok. so, just to be clear, I'm not trying to be aggro on anyone. And, I realize, other than a DNA test, no one can be sure. However, how does a crest mean she's an OE?
The crest proves that she is not a pure Barred Rock.
Olive eggs prove that somebody is an Olive Egger.
Since some Olive Eggers do look like your barred pullets (the crested one and the not-crested ones), the simplest explanation is that Hoovers sent you some Olive Eggers, either instead of Barred Rocks or else mixed with some Barred Rocks.
I don't have a camera on the nesting box or inside the coop but she's the last chicken I'd expect to be laying; period.
In the photos, it looks like her comb and wattles and face are very red (more than some of the others.) The pullets with the reddest faces are usually the ones that start laying first. So that is why I think that she easily could be one of the pullets who is laying eggs at the present time.
If they were all laying and you only got one olive egg each day, I would bet it came from her. One odd chicken, one odd egg, mystery solved.
But you actually have 2 olive eggers (and may have more, when the rest start laying), so it is NOT as simple as just finding one bird who doesn't match. I think the olive eggs are more likely to come from the barred birds, and less likely to come from the lavender birds, due to which coloring is more common in Olive Eggers.
And, the assertion that the hatchery messed up seems to be a fallback position to take if there is no other likely reason. I understand mistakes can happen as we ended up with one rooster out of the 8 BPR pullets we ordered (may his prolapsed vent and he RIP.) I'm truly curious about the assertion that mistakes are common at the hatcheries as I'm not in this to keep chickens as pets and just ordered a batch of 16 Australorps from Hoover's for early March delivery. Can I really expect not to get 16 female Australorps from them? fwiw, I've gone back to Hoover because Murray need's a 25 chick minimum before April 1 and none of the local farm store's (Bomgaars, TSC, RK) seem to be able to tell me that their chicks are immunized against anything (it's retail, i get it).
When ordering from a hatchery, you can expect most orders to be fairly close to correct. If a particular hatchery made too many errors, word would spread and no-one would order, and they would go out of business.
But with all the thousands (probably millions) of chicks that get hatched and shipped, some mistaked definitely do happen. As you've experienced, there can be wrong-sex and wrong-breed mixups.
There can also be chickens that are the correct breed & sex but have something "wrong" because the hatchery flock was not being carefully selected for the right traits (single comb chicks in breeds that should have rose comb, clean faced chicks in breeds that should have muff/beard, tiny breeds that are not small enough, big breeds that are not large enough, patterned breeds that are a bit mis-marked, etc.)
If you want chickens that have ALL the correct traits for their breed (any breed, from any source), you need to either buy adult chickens after inspecting them to see if they have the right traits, or buy more chicks than you need and plan to keep only the best while eating/selling/rehoming the less good ones.
But if you want a flock of mostly-correct chickens that are healthy and good layers, it is usually possible to get that by ordering chicks from a hatchery.
