How set different images (Cycles) for each camera output, without Scenes?

Hello,
how i can use different background images for each camera? I can´t use Scenes, because for my purpose that´s are very inappropriate.

Render engine is Cycles/GPU, Gooseberry Blender 2.73.x (from builder.blender.org) and i am looking for any solution in which i can use photo 1 as camera 1 background (render output 1), photo 2 as camera 2 background (render output 2) etc… I need lock every background image only to one camera view.

Can i Import Images as plane an set up in cycles material any thing, that lock this image to one selected camera?

All objects is shared for rendering, but background images are different for different cameras. All objects are in one scene, but in different layers. Background images overlap in plan view and when you turn all at once, it causes overlap in other render outputs.

timeline markers – http://wiki.blender.org/index.php/Doc:2.6/Manual/Animation/Basics/Markers#Using_Timeline_Markers_for_switching_Multiple_Cameras

Thank you.