Interesting idea to double layer. How to make double layered Roman blinds so you can leave the light shades down in the day to filter light, and the darker shades at night to block from the road/outer lights, etc.
How to Make a Faux Roman Shade with this secret trick! A great way to get the roman shade look on a budget!
Enjoy the View With a Voile- Woven Voile Mocha Roman Blind