Stereo HMD and experimenter's monitor

[Vaquero]

Hey! I'm pulling my hair here. After 1 year I picked up the same problem again.
This time I've got one computer, an Oculus DK2 and 2 monitors, and Vizard 5.7 Enterprise. When I start my script, the person wearing the Oculus sees the vr as expected, and there's a window on the monitor that pops up and displays a stereo view of the oculus rendering. Now what I need is an additional window that renders the same scene from a stationary point of view in non-stereo (mono), so I can see the person's avatar from outside.

I tried the Cluster Master, which opens a second window, but it does not display the viewpoint I want. The dk2 is set up to only display on master.
Everytime I try to add a new Custom Window for the monitor (subwindow disabled) for setting it up to be only displayed on client1 in vizconnect, I get asked if I want to replace the dk2 with this one. Well, obviously I don't want that, because the dk2 just disappears.
From the documentation I get this: »Co-presence is a feature that allows multiple users to share the same virtual environment.« »Note: Co-presence is not supported on a local cluster.«

So how do I render the same scene in an additional window on the monitor from another point of view?