Hello! Thanks for the review, I'm glad the tool is useful for you.
Your issue sounds like a common challenge with Blender's interface when you're starting out. To close the extra view you mentioned, you can right-click the border between the two areas and select 'Join Areas'.
I hope this tip helps!
As a very visual person, this addon is really cool! It's really nice to see the different viewports all on one screen in a much easier way (for me, anyways.)
My only gripe with this addon is that it takes away the object list. Also, this might just be me being semi-new to Blender, but I can't figure out how to turn it off and make the second window the addon creates go away with it.
Otherwise, keep up the great work! :)