Octoprint can only connect to 1 printer at a time, so if you want to use 2 printers at the same time you need 2 separate instances of octoprint. I use portainer so passing through a device is just a matter of finding the device path on the host machine and plugging its path into the portainer config under the runtime & resources tab. In a docker compose you’d use the devices key, for example
devices:
- /dev/ttyUSB1:/dev/ttyUSB1
You will likely need to create a separate alias for the host USB path though because devices can be found in a different order every reboot so the path will change. The USB device alias will be based on the device vendor and product id so it will be persistent. https://michaelgreenhill.net/persistent-addressing-for-usb-devices-in-linux/ is one site that explains the issue and how to deal with it
No the person you replied to but I have the one from https://whambam3d.com/collections/fbs-for-resin and love it