I changed the viewport-cameras, so I have perspective, top, left, right.
Upon reloading my scene however Maya just set one viewport to the exact camera of one of the other viewports(viewport-panel/view), e.g. now I have two left views, no right view.
When I try to change this by selecting a Predefines bookmark, say for the right view, the other viewport with the same view changes as well.

What is happening?