They are Model 103B which includes a Holland & Holland style self opener system.
Second set of barrels are choked very tight, perfect for Grouse & High Pheasant (You only mention choke on the more open set for each gun.)

Previous owner used them to very good effect on Grouse.

Full & Full on gun # 1 to take the birds early on, and then switch to quarter & quarter on gun # 2 to kill numbers three & four birds.

Open chokes work well for walk up or classic/traditional Partridge over hedge rows

Full & Full for tall birds & Grouse