I thought this got beaten to death on some thread in the past.
Your speaker is a non-linear impedance/resistance and the cable also has resistance. Even when you apply a linear voltage to a driver, the current flow is nonlinear as a result.
By biwiring, you are moving the true ground point directly to the amplifier from the speaker’s negative terminal. You remove the inter-driver non-linearity/cross contamination (back and forth) that occurs through the crossover between the different drivers (tweeter, woofer, etc) mentioned above.
Maybe, if you had some crappy speaker with a single full range driver, it doesn’t matter (not applicable). On a regular speaker with multiple drivers, it does matter though the audibility impact of biwiring can vary due to the driver and crossover design.
Low info dudes may claim bi-wiring does nothing. Truth is...it actually does something...that you may or may hear. If you didn’t hear it, great for you.... don’t bi-wire and do whatever, save yourself the cash for an extra cable. Return the extra cable and get your money back.
Good luck.