I think the tape is from WWII and the GIs called it duck tape.
Was never intended for ducts, saw something on one of those science or discovery channels about it.
The metal stuff is truly duct tape, used a ton of it back in the day to make ground planes for two-way radio antennas on the underside of fiberglass truck cab tops on big rigs and ambulances.
Tony & Lori
1989 Country Coach Savannah SE