cl77 carbs. one has two pin holes, the other has only one

[sotxbill]

rebuilding carbs on 1st cl77 in SA.. when cleaning and checking, I noticed two holes that go up the carb body on either side. These little holes are visable looking up at the bottom with the float removed. they then go up on little tunnels that you can see on the out side that go up the slide. One carb has a vent hole to the outside up high and the other side is cast close.(left carb)

the right carb has a vent hole on both sides up high on the slide body at the top of the tunnels..

what gives?? The tunnels look like they go up into the choke slide area and may work when the carb is on full choke but I can tell for sure. or maybe they are just a hole to the atmoshere. Any ideals why the two carbs are different?

thanks ahead of time.. Bill