pv currently allows the user to create multiple equivalent channel groups by just running the "group" action multiple times: 1.) Select the first two channels. 2.) Run the "group" action from the context menu. A new group for D0 and D1 is created. 3.) Run the "group" action from the context menu. Another (equivalent) group is created. I don't think there's a point in created equivalent groups, so the GUI probably shouldn't allow it.