Since the included regulation target is 2.5" apart from left shot to right shot @ 50 yards, I'm going to assume that the current regulation will yield inferior to 5" at 100 yards *unless* with proper break in I actually shoot better than Sabatti's regulator does under similar conditions.
All this is assuming that the right bullet hole is from the right barrel and the left bullet hole is from the left barrel which the targets for the Sabattis doesn’t indicate!
If that target is, in fact, a true indication of the right and left barrels being side by side at 50 yds, and the rifle was properly regulated the centers
of both barrels individual groups will remain side by side to infinity.
Of course like any other rifle one barrel’s group will get larger as it moves farther down range, but the center of that barrels group will remain the same. What this means in a double rifle is, when the double rifle is properly regulated the center of each barrel’s individual group will remain on it’s own side of the aiming point which is just as it is on the rifle its self, the sight half way between the right and left centers of the bores of both barrels! In other words the properly regulated double rifle shooting properly loaded cartridges the centers of each barrels individual groups will remain parallel to infinity! The shot centers are not supposed to cross at any distance! Again in other words if both barrels are hitting the same hole at fifty yards or any other range the rifle is crossing and not regulated properly, or not shooting ammo that is correct for the regulation! The composite group of a properly regulated rifle will be a slightly egg shaped with the aiming point at the center windage wise!
Double rifle barrels are not regulated to any given range, they are regulated to shoot side by side no matter the range! The statement that a double rifle is regulated at 50 yards, or 100 yards only means the the fixed sights are cut ot be dead on at that range, just like a single barreled rifle with fixed iron sights they are cut to hit point of aim for windage, and elevation at the range engraved on the sight, with hold over for longer range and hold under for short range. It has nothing to do with both barrels hitting one hole, because they do not, they shoot side by side on each side of the aiming point at any range!
The above misconception that double rifles cross at the sight's regulated range is the reason people think a double rifle is useless if shot past the sight's zero distance! A double rifle is as usefull as any rifle with simular chambering and iron sights at any range! I assure you that you certainly do not want to stand at 300 yds thinking I wouldn't be able to hit you with any double rifle I own!