What is the problem?
Is it possible to have 2 pi's that are controlling 2 3d printers to send a signal to one monitor split up?
What did you already try to solve it?
nothing. Don't know if it's possible;e./
serial.log or output on terminal tab at a minimum, browser error console if UI issue ... no logs, no support! Not log excerpts, complete logs.)
Additional information about your setup
OctoPrint version, OctoPi version, printer, firmware, browser, operating system, ... as much data as possible