What it comes down to is that somewhere along the line someone modified the DC+ lead at the regulator to add an additional output lead. This is something that can be easily done as long you have the proper crimping tool and terminal.
All us probably have seen wiring harness mods though most are probably hacked wiring using just any color wire that is they have access to. I recently straighten out a Command that there four color wires on the same lead with the wires simply twist together and clear packaging tape. No wonder things shorted out.