There have been times when I’ve needed to have two different areas of OneNote open at the same time, and this tip has been a lifesaver in terms of getting everything to display properly.
When you have OneNote open, use the View > New Window Ribbon Bar option:
The result is that you now have two instances of OneNote that you can use at the same time. This is great for copying information from one notebook to another:
One Minute Office Magic 