Since I use KeyShot mainly to play with ideas for nail polish I'd find it amazing if you could add an option for a second flake color on the Metallic Paint. And if I could wish for the moon it'd be so cool if the flakes could have a duo chrome effect - wouldn't that look neat on cars too?
(http://the-swatchaholic.com/wp-content/uploads/2011/11/china-glaze-glittering-garland-nfu-oh-56-ozotic-pro-elytra-530_01.jpg)
(http://the-swatchaholic.com/wp-content/uploads/2011/09/guest-post-fashion-polish-yves-saint-laurent-wintergreen-franken-venom-toxin_01.jpg)
Cheers
You can control the metal flake color with a specular map.