Hello Samuel,
I assume you use Automation Runtime embedded directly on the PPC (no Hypervisor with Windows / Linux as GPOS)?
In that case I’m not 100% sure, but as I remember, AR can only use one of the system’s graphic units, in case of a PanelPC only the internal one where the directly mounted display is attached to.
To show the VC4 visu on a 2.nd screen, you could use a Terminal connected via Ethernet to the PPC: for example, the 2.nd AP together with a small PPC like PPC2200 and a GPOS system or a T50/T80 Panel, and show the VC4 visualization via VNC viewer on that device.
Best regards!