AK-74 has 2 bayonet lugs?

Just noticed this. Why does the AK-74 have 2 bayonet lugs? One on the gas block and one on the FSB.
I know the AKM uses a lug on the gas block since the bayo hooks on right in front of the front sight and the butt of the bayo reaches back to the gas block to clip on there.
On the 74, because of it's long buzzle brake, the bayonet sits further forward and clips on at the FSB.
So why did they keep the lug on the gas block? Especially since they were designing a new one anyway. Is it necessary for attaching the grenade launcher?
Just a weird thing I noticed.

 

Something tells me your rifle didn't come with a cleaning rod, making the back "bayonet lug"'s purpose readily apparent. It holds the cleaning rod in place.

 

You nailed it. The 30mm grenade launcher clips onto the rear lug.

BSW

 

Yes, it does serve to support the cleaning rod, but that could be done with a simple loop, while the one on the AK74, has the actual cut outs that would let you clip a bayonet to it. If the muzzle brake wasn't in the way. That's what I was asking about.

Thanks briansmithwins. I figured that was probably it, since the launcher doesn't seem to have any sort of loop to attach to the barrel itself like an M203. Gotta clip on to something then.

BTW The GP launchers are 40mm if I'm not mistaken.

 

Yep, their's are 40mm also, but non-compatible with M203 et al ammo.

 

my AK-74 has two lugs, rear would appear to be for accessories like grenade launchers, maybe shotguns, other attachments, fronts for bayonets.. also, i havent tried this to be sure but if you had a shorter muzzle device, i believe the bayonet could still be attached using the gas block lug like the bayonets on the AKMs