Its most likely because they were too lazy to change the effect on a specific gun so they made it where if you have those dual wield guns that all other dual wield guns will have the same gun burst animation effect
The following user groaned Kristopherr for this awful post:
Its most likely because they were too lazy to change the effect on a specific gun so they made it where if you have those dual wield guns that all other dual wield guns will have the same gun burst animation effect