Independent monitor switching between sessions

[Fofo]

I am running UltraVNC viewer on my computer and UltraVNC server 1.4.3.6 on the client side.

For context, I have a laptop connected to two separate monitors. " I then have an off-shore headless PC that has two virtual monitors (Virtual Display Driver installed); let us call it the "client." By using the command line I connect myself to the client's PC, the command line is something like this:
start "" vncviewer.exe -connect IPandPort -user NAME -password PWD -position 0 0 3840 1080

Afterward, the viewer screen starts up and remotes me into the client's PC. If I have the client-server configured to primary=1 and secondary=1, everything boots up fine; if not, I simply click the "Switch monitor(drive only)" button to get prim+sec. All of this behavior is intended.

However, a problem occurs when you have two viewers connected to the same client. It could either be myself having two separate UltraVNC Viewers running and connected to the same client or one of my colleagues is also connected. Either way, if either of us clicks on "Switch monitor(drive only)," the Viewer screen updates for ALL viewer screens, not only for the specific Viewer exe instance. This behavior, in my opinion, is not a desired behavior.

Why do I want to be able to switch monitors independently of every viewer exe that is connected to the same client?
I want to be able to have two separate viewers, one on each of my monitors, and have each viewer in fullscreen mode. To achieve this, I need to use the "Switch monitor" button without switching it on my other Viewer (I do not want them synced). Fullscreen with two monitors is currently not possible because the Viewer will try to fullscreen on my side and fit the remote content (two screens) into my one screen (intended behavior). Furthermore, some of my colleagues have different monitor sizes, and some work only with a laptop (one screen) and are therefore forced to utilize the "Switch Monitor" button to switch between the two remote monitors and can't utilize the spanning of both monitors mode (prim+sec) as it would not fit. The autofit is not an option either due to the resolution etc.

Therefore, is there a way to connect two exe instances of the viewer to the same client/server and switch monitors without switching on all instances?

Note: I even tried having two different ports when connecting, 5913 and 5915, when I connected if that would make a difference.