Want to see two Microsoft Excel files side by side? No problem, it’s easy. Want to see one file in 2 or more points of view? It is also just as easily, just need the help of the New Window button at View ribbons tab.
So, you need to click the New Window button before you adjust the layout. After that you can Arrange All window as you want.
Do not open another Excel file to not narrow the field.
Arrangement of such a view is usually used for data processing that much so it is easy to compare data.
If you do not use this method, you will minimize the confusion of having to perform and maximize file. Or if you have more budget, consider using a second monitor.
With this way, you are free to edit the file on every window that will automatically update the contents of both windows (because actually it is one file). If you create two view by opening a file twice, one of which will be read-only status.