Thats the supercharger man!!! It is probably more for idle than anything else. They probably added the second one after they found the sump one filled with oil and caused oil to blow out the lower vent which is meant for intake air. I'll bet they intended for this engine to be a clean runner and not leave oil goo on the plane that would happen if they just vented the case to atmosphere like others do.
I have two of these NIB that I bought for my B-25 and found they are too big, would have to really open the cowls for them to fit, and replaced them with a pair of Saito FG-30. These wi more than likely go into my someday to be built P-61 Black Widow. Now that I have an engine test stand, I plan to run these up and see how they do.