With two or three displays, sometimes the login panel shows up on one screen only, but on others, it may be two, or may be three. Is there something in tdmrc that I'm missing about GreeterScreen=, or not understanding (near top of file) that can control how many on which greeter appears? Absent a specific GreeterScreen= setting, typically either the lowest resolution screen seems to acquire focus, or first choice goes to connection using the oldest technology (1VGA>2DVI>3HDMI>4DP) if not more than one having it.