it has a 1 way valve in it. you will just get fumes from the cam cover area drawn into the inlet on overun (or when the manifold is in vacuum) for emission reasons.
its not need. you can either block it off and just run one breather (the one on the left side of the cam cover) or remove the one way valve and fit a pipe and breather filter, or a pipe to an oil catch can.
i would personally go for keeping it but piping that was well as the other breather to an oil catch can.
then you can block off where the pipe went into the inlet.