Hi, scenario:

• First use "Find usages" and results are written in Search Results output pane.
• Then use Ctrl-Shift-F and results are again written in the same window, overwriting earlier results.

This brings idea that there could be several Search Results output panes. In Ctrl-Shift-F "Search for.." screen there could be selection to which Searh results output pane you want your results. Or then just have different Search Results for "Find usages" and advanced Find.