Possible Problems and Solutions

Using the new Render pipline system, and the camera's are all acting strange, and overlapping on the render texture.

Enable Opaque textures within your render pipline asset.

Every render texture / camera produces a double image, without 3D enabled.

This is common when using VR packages, the solution is to set all cameras (except for your VR camera)
to one eye, as they are probably set to Both.