I'm not clear on what you're trying to do. Is the idea that running two cords from the amp to the speaker cabinet will somehow change the impedance? If so, forget it. Is the cab wired for "stereo"? If so, then powering both sections of the cabinet will get you more power than powering only one.
So, what are we looking at here? Mono amp, mono speaker cabinet? "Stereo" cabinet? What impedance is the cabinet or its sections?