Distributed rendering from a free (non-camera) view can lead to incorrect results. If you see incorrectly overlapped objects, render from a camera view.
This message warns about possible errors that may be caused when using distributed rendering with free (non-camera) view. Since 3ds Max command line rendering, which DR takes advantage of, has occasionally problems of correctly restoring view position, it is always suggested to use distributed rendering with Camera view.
Similar error message: The scene should be rendered from a camera named 'xyz', but there is more than one camera with that name in the scene.
See also: How to use distributed rendering?