I didn't say anything about the Road Runner badging. Again, in model year 1972, the "GTX" badges were stick-on. The "Road Runner" badging was pinned, on later model year Road Runners, the "Road Runner" badges were also stick-on. In my own dealer experience, I was asked to remove "stick-on" badging from several cars, new and used, for various reasons, not uncommon.
If the car you had was a “U” code (440HP 4V) from the factory, it was a Road Runner GTX. It “should” have had three “GTX” badges when it left the factory. While official documentation to that effect has yet to be found, i.e. engineering diagrams showing exact locations, that leaves us only with examples or photos of original examples. The closest we get is in the parts manual, showing the deck lid GTX badge application in the general (wrong) location relating to the circle bird decal. Auto manufactures don’t go to ANY expense adding anything to a production car without a reason or a plan. Yes, there have been production mistakes, normally these mistakes are more omissions than they are additions.