HOWTOGAMEDEV ALPHA

How to render from two cameras at once. How to render GUI layer seperated. Unity3D.

Newly imported file does not show new animations unity3d
Set the Clear Flags of the camera to depth only so that the background camera render is visible underneath. This property determines what to do with the transparent or empty space in the render.

Set the depth on the camera that will render last to be highest. The camera that renders last shows up on top of everything else.

Culling masks let you control which camera renders which layers so they are also worth a look.