Dual AM antennas on old cars

[KlassikKountry]

After discussing WMID's reception with Tom on the Jersey board I was wondering, I can barely remember the cars from the late 50's and early 60's with the dual AM 3-4 section antennas mounted on the back of the car, one on each side.  My question is, did they really improve AM reception and were they both hooked up or was one just for show.  I was a bit young to remember the actual reception when you had one or two or the standard antenna mounted on the drivers side of the front fender.