I was able to bypass this issue using an Autohotkey script that switches windows before switching PCs with Multiplicity. However, when the game is active on the primary PC, and I'm controlling the 2nd PC, the mouse moves on both. So this is the next item I need to tackle. Would appreciate any assistance. 

Awesome, thanks for forwarding it along. I'm really impressed with the product so far, and the audio streaming is a huge advantage over your competition. If I can get this double-mouse thing resolved, it'd be perfect. 

Interestingly, multi-boxing SC is allowed when on 2 PCs. But I've only got one account and the second PC doesn't have the horsepower to run it anyway. That said, it does not happen if the primary PC isn't running SC. Also of note is that the keyboard inputs don't go to both PCs when switched to secondary; just the mouse. Switching to Windowed, Borderless, or Full-screen modes in the game does not make a difference. Current work-around is a second mouse. Not ideal, but workable if we can't figure this out. My assumption is that it has something to do with how SC uses DirectInput or something, but that's just a guess. 

Hello,
I have forwarded your problem/question again to Stardock Support Team for their assistance. Please keep an eye on this thread for any updates. We appreciate your feedback and patience.

Basj,
Stardock Community Assistant

That is correct. I'm quite impressed with the product in general, and in fact purchased it then upgraded to Pro shortly thereafter. Consider me a satisfied customer! But as I'm sure I'm not the only one who uses this for games (or switching away from them as the case may be), perhaps this can just be feedback for a potential patch some day? Thanks for your time. 

Not really multi-boxing per se, as the second PC doesn't run games. I haven't tried it with other games; just Star Citizen. Perhaps I should try some others out. 

You should be able to work around this by using sandboxie plus to isolate SC on your main if it isnt playing nicely with multiplicity