Possibly dumb question: can I use two cable runs for each channel, not bi-wired?

I'm moving my components into another room, in order to shorten the existing 30 foot cable runs to about 10 feet,
and will run the cable through the wall between adjoining rooms. I'm wondering if I can make use of the resulting "left-over" lengths of cable by doubling up each run, utilizing one pair of binding posts for each side. Has anyone tried this? Question #2: should the pairs be jointly terminated,or should I use bananas coupled with spades, so that there are 4 terminations at each post? I haven't sen any references to this in the past, so it may well be in violation of some basic rule of physics, but I thought I'd ask, anyway.