Hi, I also wanted to explain my need for a mirroring option in LibreElec Kodi.
I run a media center in the back of my Defender so the kids won't complain on long trips. I have used several configurations of Raspberry Pies and HDMI Splitters, and then I thought that a Raspberry Pie 4 would allow for a nice low power multi-screen option, without the need for a splitter, but it doesn't work.
So one other request is that audio can be duplicated through each hdmi output as well. This allows audio to reach each screen independently...(which the kids might plug headphones into)