Good luck with boresighting and stuff like that in combat conditions, accuracy would suffer with that system.If you suffer from barrel ablation, it would still probably be more weight efficient to have both barrels, and possible a third, emplaced on a central rotary mount rather than duplicating so much autoloader.
All depends on particular autoloader design, if there is an autoloader at all.
And it comes with a bonus in form of ability to do a quick 1-2 shot if needed, plus some redundancy against damage or malfunctions.