multiple cameras or timepoints?

Hi, trying to camera-map the objects in some voodoo matchmoved footage, back in Blender. Would be really useful to either have 2 windows showing the scene from the voodoo generated camera at different time points or alternatively to display 2 different camera viewpoints simultaneously (in which case I can fake the above by using multiple cameras). In either case I would also need to display different background images or sequences in both windows.

At the moment if I have 2 camera windows and select a new camera in one, both change; same with the background image or film.

Any ways of doing either of the above? Thanks