Audioqest calls it single or double biwiring when using a single or a double cable. Most of AQ's speaker cables use multiple conductors of different gage, which make it fairly easy to single-biwire. Their most-common conductor sizes are 16-, 18-, 19-, and 21AWG.
However, many (including AQ) believe one is better off separating the different magnetic fields created by the low-pass and high-pass sections of the crossover by using physically different cables. IOW, they believe you're better off using 2 separate medium-price cables rather than one very expensive single cable no matter how many pairs of conductors it has.
I double biwire my 2- and 3-way speakers. (Virtually all 2-way speaker systems use a high crossover point; most 3-ways use a low crossover point.) The former combine bass and midrange in one section and hence benefit from the 'quality' and 'quantity' parts of the cable, while the tweeter-only section of a 2-way benefits from the very-highest-quality conductors while not needing much material for the low-current treble. Three-ways run bass on the bottom and combine midrange and treble on the top. The bass requires good (but not great) conductor quality but a lot of it. The MR/treble benefits from the very-highest-quality conductors but doesn't need quite the high-current capacity that the bass does.
On my 2-ways, I use AQ's KE-6, a 4-pairs-of-silver, DBS cable, on the bass/MR and KE-4, a 2-pairs-of-silver, DBS cable, on the treble. On my 3-way center, an Aerial CC3B, I use inexpensive Type 6 with 3 pairs on LGC copper on the bass, and KE-6 on the MR/treble.
All 3 of these front-channel speakers have never sounded better.
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