The shotgun barrel length is the number one thing that will affect the spread of the projectiles as they come out. A competitive shooter told me that the shotgun barrel length will affect the spread even more than the choke. If you’re measuring “damage” by spread, then I suppose a sawed-off shotgun has the potential to do a lot more than a standard-length shotgun.  However, a longer barrel also increases muzzle velocity because it gives the gases more time to push on the projectiles with full force to a standard shotgun, so if you’re measuring “damage” by penetration or stopping power, I would say that sawed-off shotguns has the potential to do less than a standard-length shotgun.