yes you can, guns like the mannlicher m93, the D models weapons. These are legacy weapons that were from the older pre-merge update. They used to be the stock rifle for all units but the merge just made everything messy.(Kar 98k(D),Kar98k kriegmodell(D) ,M41(D) and Mosin M1938 carbine(D)).Basically all the legacy weapons would occupy the start of the lists which are all duplicated weapon from the normal tech tree. Even grenade and parachutes have a legacy version, Explosion pack and the american/british parachutes can be duplicated.
Only thing I cant sell are the squads which has now become annoying when you mess up which one have the upgraded vehicles(no joke I have 2 T-34-85(D-5T), IL-2-37, Yak-7B, and a legacy P-38G1) these duplicated vehicles also consumed twice the value since you have to upgrade them independently.
Not just that, they also locked the better vehicles to the pre-merge squad so some better vehicles I have cannot be used with the squad which need more research points( I am still locked out from using the T-28 and Panzer III J due to them being locked to the 2 squads), Plus their upgrade path only reaches the same vehicles but at a exorbitant research cost for the T-28 legacy squad, a level up from lvl 7 to 8 will cost 15710 points which is equivalent to 4-7 levels worth for a standard post-merge squad