Dual rear radio antennas

[dibbons]

My 1965 Valiant Signet convertible (273 2 barrel auto) has holes for two rear antennas on both sides of the rear window. Does anyone know if that was a factory installation or aftermarket? Thank you. (no build sheet).

 

[YellowDart69]

I remember these cars since new. I never saw anything but a single antenna on the right front fender.