We talked about a similarly described 20ga. Repro a while back. I do not believe Parker Reproductions ever offered that as a finished product (other than "in-the-white" A-1 Specials). Instead I believe the gun was originally Repro-style case colored that someone had removed the coloring leaving it similar to having a dull coined finish. There's a pic in the linked thread below:
https://parkerguns.org/forums/showth...ghlight=nickel