When I link two IFC files, the same IFC parameters are assigned to corresponding shared parameters, but these parameters doesn´t have the same GUID.
This causes the schedule to show the elements is different columns, as you can see in the schedule image.
As a test, I exported two IFC from Revit files and them linked then in an empty one.
Also I included the shared parameters file created by Revit for each link.
There should be a way to make this process uniform.