There are Sage Green NB-6's.. the flap is the design. They were made by different companies using the same design.
Hayden's chute left behind is not an NB-6, it is a P2-B24, hard to find info on it but I found the Pioneer P3 called a civilian chute and also supplied to the military..
So, maybe Hayden's P2 was called a civilian chute because it was both civilian and military whereas the other chute was military only.
Hayden would not have known that, which is why he disputed the description in the FBI docs calling it a civilian luxury chute. That suggests the description was falsely attributed to Hayden.
We don't know the model of container used by Cooper other than it was a Pioneer. Cossey called it an NB-6, it could have been, we just can't use Cossey's description to confirm.
Initially, Hayden's chute used by Cooper in documents dated November 25th was described as military Olive Drab w tan cotton civilian type harness.
Cossey interviewed on November 26th described it as an NB-6 Sage Green Nylon container and Sage Green nylon harness.
IMO, Cossey was describing his back chute he had assumed was taken from Issaquah but was not.
Everybody confused yet..
Cossey's actual Cooper replica chute.. Sage Green