Blender ships with an addon called Material Utilities. It is not enabled by default, so you just need to go to preferences and turn it on. Shift Q brings up its menu and the documentation link is available via preferences. There is a function called Copy Materials to Selected that might be what you're looking for. I just gave it a quick test and it seems to work OK.

And yes, Blender appending numbers to everything is a royal pain in the proverbial.