Pretty sure dual horns were an option whether you got deluxe or not. Not positive though as mine was an early Van Nuys build as well and had them both when I got it. I don't think you can tell by the wiring harness if it had one or two because the connection will be there regardless.

BTW. Who in the hell said the straight bar vent balls were camaro??? They were an early build thing not a camaro thing.