Simple, pull it out and shake it.
If it rattles you have a check valve, if you have an orifice type there will be a small hole about .1" on the big end and no rattle sound when you shake it. You may have spray some solvent in it to lossen the check valve, if its a valve type.

 

When I had my custom Valve Covers made for my SSR I only had the PCV put on the passenger side cover. This way the single PCV goes to a catch can and then to the intake tube. Never a leak or problem and I have been running this way for a year.