I'm not so sure of the need for a dual valve.I can see the need to stop the winch line suddenly unwinding if a hose should burst.But i find it harder to imagine a case where a burst hose would cause the winch to wind in in a dagerous manner.
Personally I would not bother fitting a check valve of any sort to my hydraulic winch system if it were just to protect against burst hoses.I use synthetic winch line,and I have no doubt that the line will snap a hundred times for each time a hose bursts.
But I do have an overcentre valve fitted to my Milemarker for a slightly different reason.
Without it,if I winch the vehicle up a bank,and stop with the load still on the winch,there is pressure stored in the pipes from the spool valve to the winch motor.If I then go to lower the vehicle on the winch,it will drop uncontrolably until the pressure in the lines has equalised.Typically it will fall backwards two or three feet - an unpleasant experience.
My overcentre valve bolts directly to the winch motor - no pipes joining them.1/2" bsp ports comming out of the valve.They are available for any Danfoss motor,or copy of a danfoss motor (which is what type Rs are).I bought mine from Harrier Fluid Power,or what ever their name is.I could take photos if needed.
Best to decide what you need,then order it.Good advice on the confusing world of check valves is hard to find,even amoungst suppliers.
Excellent link there Errol!