Never mind higher pressure which is always an interesting proposition in a break open rifle action...
Tech corner
On the technical side, yes, O/U doubles are typically easier to regulate (hence cheaper to manufacture) because both barrels are in the axis of the action/stock as opposed to one on each side of the axis, resulting in a yaw when the rifle is fired, which the regulation is intended to compensate for...
So, in a perverse way, the rifle "may" still regulate (place shots from its two barrels together) even though not to point of aim (what with higher velocity and increased recoil) because being an O/U, there is no yaw to compensate for, to begin with... By the way, this explains why O/U continental doubles in 9.3x74R or similar low recoiling calibers are much more forgiving of ammo variations than SxS nitro express rifles with much greater recoil, hence an amplified tendency to yaw...
Also, FYI, the description in the gunbroker ad is risible: "
made in Germany by Steyr-Mannlicher for Italian gun company Armi Renato Gamba." Unless I am considerably off my rockers (?), Steyr-Mannlicher never made a double rifle. Most likely it is a German guild made and proofed, hence the German proof stamps, (barreled?) break open action, stocked and finished by Gamba, hence the Italian proof stamps, imported in the US by the US Steyr distributor... As to how a double rifle action likely designed for the 9.3x74 R (49,000 PSI) fairs with .375 Wby loads (65,000 PSI), well, I would just love to spend five minutes with this rifle and a few cuts of cigarette paper...
Oh, but, I almost forgot. Looks like the buyer will get what he pays for. Starting bid $0.01 with no reserve. $2,625 as of this writing... Smoking deal for a double .375
Well, at least it is not a soft steel Italian guild break open action...