In this 3d model space multiple camera are placed.
One camera is desired for portrait shot (1200 X 1800 pixels)while other in landscape (1800 X 1200 pixels) shot.

But in blender when one camera setting is changed to the landscape proportion the other automatically changes to landscape (which is not desired).
However there is some workaround that to change the orientation of second camera so that other camera remains undisturbed (but this is annoying to look at). Is there any proper method to resolve the Orientation Issue.