I'm not sure this is a bug... Maya has four viewports, and each can be set to show a different panel of information, including camera views. You can and should be able to set multiple viewports to have the same view of your 3D scene--you can then further customize them by showing only certain types of geometry in one, or doing a 2D pan/zoom, or only showing textures in one but not the other, etc.
In your toolbox on the left of your screen are a series of layout buttons that should let you reset your viewports to a default; 'four view' is a common starting point that should use one each of the four default cameras for each panel's view.
If you're describing something different, like multiple viewports showing not just the same camera but the same panel (e.g. two copies of the Outliner, the Hypershade, etc.) that's something different... I'm not sure what might cause that.