An idea of how to make a 3D TV set.

Has anyone ever tried taking two LCD screens, placing them one over the other and using a common backlight to make a 3D TV?  Since every TV channel is now 4 channels they could easily broadcast an offset image on two sequential channels to come up with a 3D image.  I am not sure the backlight would be able to penetrate both screens or how that would react to having two screens in front of it.