For now, I think you would need to run two different major releases of PhotoLab/OpticsPro simultaneously to do that - or run a different application to view images on the second screen. I don’t know of a way to start two instances of the same major version of PhotoLab, one for each monitor. One could extend the desktop across two monitors, but one still can’t presently view two different images side-by-side in PhotoLab except in the filmstrip. See the link below for a discussion on that: