Bi-wiring is a waste of good speaker cable. Stick with a single, good quality cable to each speaker...
See this thread. My comment in that thread, while obviously somewhat tongue-in-cheek, I think pretty much says it all:
I think it also depends on your speaker. Some are designed to be run bi-wired so if you only run them single wired or single wired with jumpers, the sound isnt as good. Bi-wiring vs. single wiring with jumpers made a huge difference for the better with my Unity Audio Signature 1's. For other speakers this might not be the case so an option might be to borrow a set of cables the same as what you already have, or a bi-wire made set from The Cable Company (they let you evaluate them at home) and see if there's a difference thats worth it on your particular speakers.