3006 is not a multi-group talk group. What you are seeing is 3006 being selected by the system as the "super group" in the multi-select call from the console. In the system, when a patch or multi-select (multi-group) call is initiated, the system will announce over the control channel that the talk groups included in the multi-group call are placed into a "super group." The super group will be one of the talk groups involved in the multi-group call. When you see numerous talk groups patched or multi-selected with 3006, it will be the system announcing that those talk groups are involved in the multi-group call, and that talk group 3006 will act as the super group for calls on those talk groups until the multi-group call is torn down.