No. In the pre-industrial 18th c. and earlier, when guns were still made by craftsmen , most of the labor ( and so, most of the cost) was in making the barrel and the lock. To make a double-barreled gun required not just two barrels and two locks, but a right-hand and left-hand lock: so, one of the locks had to be different- a problem if you are trying to make as many locks as possible. Making a double-barreled musket for a soldier was about as expensive as making two muskets.

However, there were volley guns. The most famous of these was made by the English gunsmith Nock, and intended for use on ships. It had seven barrels, and was supposed to be used in boarding another ship or repelling boarders: blunderbusses were invented for the same sort of purpose.

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