I have done this a few times. If I pitch brett it's usually pitched with the main strain. That being said I've pitched multiple strains of Brett into an all Brett beer as well. As for clean yeasts, I've blended WLP550 and WLP530 in a BDSA. I wanted to blend those two profiles together. Turned out pretty great. Blending Belgian strains is fun.
Drinking: Wallonian Farmhouse Ale - IIPA w/ Mosaic, Citra and Simcoe - All Brett Ale (Claus and Trois)
Bottled/Conditioning: BDSA #3 - Farmhouse Saison with Brett Brux and JP Dregs
Secondary: BDSA Rum Barrel Aged - Wild Ale - Sour Saison with Peaches - Year 1 Lambic - Berliner Weisse
Primary: *Empty for now*
On Deck: Saison Blanc - Oud Bruin - House Sour for Blending - Biere de Miel