Duplicate Windows visually copies any window in OS X live and on-the-fly. It’s like display mirroring for individual windows!
Duplicate any window. Select any window on your Mac, and get an instant resizable copy that stays up to date with the original.
Monitor anything. Don't disrupt your workflow. Watch videos. Watch a sports game. Monitor your servers. Keep an eye on any window you like. Just duplicate it, tell it to stay on top, resize it to just how you want it and get on with your work.
Presenter Mode for any software. You can duplicate windows across monitors. Drive a software demo with your notes right along side on your laptop screen, while only projecting the software you're demoing. You can even duplicate as many windows as you want.
What’s new in version 1.6.2
Updated on Apr 21 2021
Fix horizontal flipping to work with more screen configurations
Improve energy efficiency when a Duplicate Windows is not visible
If this works as advertised, is maintained, and has a developer that listens to customers then this has the potential to be a very nice app.
Unfortunately, not much on the dev's page and it's MAS so we have to wait and see reviews from others who have $10 to spend.
If you buy this, please let us know how you like it. It looks great from 2 screenshots.