If you really want to, that should be doable, you just have to sync the shutters of the cameras with the screen and switch the virtual scene along with it, much the same way as 3D TV used to work. At least for two cameras, that should work well enough, as the 180° shutter common with 24fps movies leaves enough room for a second camera.

As long as the same background isn’t in both cameras I think it’s doable (facing different directions for dialog) or one with a cropped closeup. Though not sure the software currently support 2 cameras.. kind of an interesting problem.

My understanding it the rendering is done at higher quality when the background is the cameras field of view to save resources.. the rest is there just for ambient light.

Of course this takes a lot of pre planning, but those virtual set ups kinda always do.