Global level materials and plant level materials

Hi,

Here is the scneraio that I have for which I need a solution:

I have created a material (A, say) at the global level and then extended it to a plant. On the other hand I created another material (B, say) directly at the plant level.

When I take out an extract of all the materials in the system how would i distinguish whether a material was created directly at the plant level or created at the global level first and then extended to the plant level.

Thanks in advance,

Aviroop