They are like one way valves. They can only flow out, not in.
I see what you are saying. Technically I guess you may be correct that since two hoses are joining to one, once they merge the velocity will increase and it will "suck" more out. Just like a y pipe on an exhaust.
Really though, you won't notice anything different. There is only so much pressure in the engine crankcase, and you can't suck out more than is there.
I think we are over thinking this again lol.