If you have a size 6 SLF bay with 2 slots you should be able to launch 2 fighters at same time currently you have two slots but can only launch one fighter 16 times
You'd need another pilot for the additional fighter, though. The advantage of the bigger bay is that you can launch a new fighter the moment the old is destroyed, with no downtime to await a new to be assembled.
I have a size 6 slf hangar on my Type-9. I can launch an NPC crew member in one fighter and have another for a multicrew commander or myself. It won't allow two NPC controlled fighters, but it will allow two player controllee fighters to operate at the same time.