Camera Clear flags not working properly on Gear VR

Ok, I see what you mean. You want the "BackGround" box to z fail behind the "Middle" box. Camera 2 doesn't re-use the depth data from Camera 1 and there is z fighting between the current content rendered by Camera 2 and the content Camera 2 rendered in the previous frame. Interestingly, while the Rift output in 5.4 is correct, the Camera 2 preview in the Scene view has the same artifact as Gear VR. It's also worth noting that on Rift, the Oculus SDK allocates the eye buffers while on Gear VR, Unity allocates them for this version.