twin groove furling foils

[Brion Toss]

Hello,
As Brian notes, it is possible to wing-and-wing stays'ls in twin-groove foils, but heavy use will harm the sail. And in any event there are better sail choices for running; drifters, assymetricals, that sort of thing are lighter, better-shaped, and easier to handle. And twin running sails are notorious for generating "death rolls". So I'd reserve the twin feature for what it's best at: quick sail changes.
Fair leads,
Brion Toss