When adding a selected resource remove it from being selected again

Basically what the title says. When i select a selected resource it can be selected again. Although this does not duplicate it so i think if it is not being duplicated it should be hidden so it doesn't clutter the interface. For example i was adding resources for a game series and looked up the game. If I select a resource from the game it should remove that from being selected again so the i don't have to scroll down more. Hope that makes sense.