Question How to Duplicate Monitors 2 & 3 (not the desktop Monitor 1)

[Cygnus1]

I have three monitors (a laptop and two monitors). The laptop screen is Monitor 1 (main). What I'd like to do is duplicate monitors 2 and 3 (but not 1). I would be doing a presentation with a control program (on 1) with the presentation showing on 2 & 3 only. The only options I see under display settings are duplicate 1 & 3 or 1 & 2. What I need is duplicate 2 & 3 only. Is there a way to do this?

Basically monitors 2 & 3 would be mirrors of each other (but not of monitor 1).

 

[Eximo]

Pretty sure only third party software can do this. https://www.actualtools.com/multiplemonitors/

It can be done in Mac OS apparently.

Only other way would be a physical splitter, so that you effectively only have one secondary display.

 

[Cygnus1]

Pretty sure only third party software can do this. https://www.actualtools.com/multiplemonitors/

It can be done in Mac OS apparently.

Only other way would be a physical splitter, so that you effectively only have one secondary display.

I've tried a couple different splitters (my first guess) but HDMI doesn't support dual displays and the USB 3.2 to DVI-D splitter still shows 1-3 monitors instead of 2 being duplicated. That software looks like it might work though it has a mirror function for a specific display so I should be able to mirror monitors 2 & 3. Thank you for answering I will contact them and ask them the specific question to see if their software can do this.