I've used multiple image canvases at the same time. Just use TargetRect to draw to whatever area you desire. I believe the default behavior is that only the top screen will receive events, but I just assigned the same message port to all image canvases and didn't really care which one was getting the event; I was going to perform the same actions no matter what.
-JT
Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution."
If you appreciate my answer, maybe give me a Kudo.
I am not a Roku employee.