If you are looking for optional room darkening capabilities, consider a shade with room darkening liner. The liner can be sewn directly to the shade or it can operate independently, offering ultimate flexibility.
Silhouette® A Deux™ Window Shadings combine a Silhouette® shading and a room darkening roller shade in a single headrail. This setup provides you with maximum light control: from translucent to light dimming to room darkening.
Duette® Honeycomb Shades with Duolite™ have two fabric panels, one made from a light filtering fabric and one from a room darkening fabric. Both panels span the full width of the shade and can be moved independently.