Is there a way to run two instances of Dorico?

I want to change the time signature of a large section of a long big band chart. I’d like to be able to have the old version open on one monitor (readonly) and the new version open on another monitor so I can easily copy and paste all the parts which are unchanged. When I do this by double-clicking one .dorico file, then the other, it appears to work but quickly becomes non-responsive, at which point I must kill the program.

You can have multiple files open, but its best to have them all de-activated for playback. Otherwise when you change the focus Dorico has to keep unloading and loading sounds (even if both files use the same sounds)