Custom Stencil to affect multiple Objects differently if Parent Post Process Material is the same

Hi Guys,

I am trying to create two post process material instances derived from the same material so that it affects two different objects having different stencil values. So if I have an outline post process and I create two material instances from it having stencil values as 250 and 255, for example, and try to affect two objects, with the respective stencil values, it does not work, only one object is affected, however if I duplicate the material and create separate material instance from the new material, it works. But this is plain ridiculous. I should be able to use same material and two different material instances for two objects. Let me know if you have come across this and found a way around. Thanks