Hello, i am trying to figure out how my 2 yellow lines that come from the engine bay should be plugged into that nipple looking thing.

I have the one yellow line and the one yellow line with black stripe. I know the yellowBlack line goes to a tank in the back of the car but i am somewhat confused about how these two lines should be connected (inside the engine bay). I see that the main vacuum line goes into a yellow nipple looking thing that has two vacuum ports in the back. It would make sense for each yellow line to occupy one of those two ports, but i have noticed in some of the vacuum diagrams on this site, the two yellow lines actually go to only one of those ports and have a rubber fork off of that one port.

Is this correct? Or should each yellow line occupy one of the ports on that plastic nipple. (and if so which side for which?)

Thanks