@d-healey Both will be active at the same time. I've run a few tests in the exported plugin and it seems to work without any issues. It's great for assigning say CC1 by default to a knob on your interface, but also allowing the user to assign CC1 to other knobs without overwriting the default.
I haven't made a pull request because it seems that some people don't want this behavior. Easy enough to tweak if you want it though!