On a set of carbs, if they are properly tuned to your bike, using just one on a two into one intake that same tuning should run the bike the same without much adjustment.
On a two carb set up as the engine runs, one cylinder pulls fuel from one carb. As the engine turns the other cylinder pulls fuel from the other carb.
With the two into one, one cylinder pulls fuel from the one carb, as the engine turns the other cylinder pulls fuel from the carb.
On both set ups one carb feeds one cylinder.
Leo