The principle behind biwiring a speaker is that if the speaker has separate crossovers for the tweeter/mid and woofers then extending the wiring back to the amp with long speaker cables, instead of the short jumper, minimizes the interaction between the drivers reducing intermodulation ditstortion. Depending on the design of the speaker it can be a waste of time or can yield some improvement. Worse case you can just double up and have a lower guage of wire which can give you a bit more control of the woofer.
Wire one speaker for biwiring and leave the other single wired, play a mono recording and use the balance control to compare them. Never know it to sound worse and most speaker cable isn't expensive.
There are some speaker cables...