I've never seen that choke marking on a Repro with a "quail 2" choke.
We've seen Winchesters stamped with WS I and WS II.....
As far as the screw is concerned, an extractor set of barrels would have that retaining or 'stop' screw but we know that all Repros were made with ejector barrels.... or were they?
Pretty odd also that the 00 frame size stamps were stamped with two different dies.
Could this set of barrels have been ordered this way for some particular reason?
This is really an enigma...