When using 2 weapons of the same model (name can differ as long as the model is the same) the weapon dye of one model is copied to the other weapon when it is hotswapped.
The weapon dye color that actually shows is the one of the weapon that is worn when logging in or zoning.
The weapon color of the item that is not yet equipped will simply copy the one that is currently equipped when it is swapped in.
This happens consistently. It's a bit confusing when you want to keep track of which weapon you are using these weapons because dying them in different colors will of course not help.
Thanks.