This plugin simply gives you the ability to add multiple webcam views on a single page.
Note: This does not configure additional streams or manage any streaming technologies within OctoPrint. You may be able to follow the instructions over here to get the second stream.
Install via the bundled Plugin Manager or manually using this URL:
https://github.com/jneilliii/OctoPrint-MultiCamView/archive/master.zip
Add camera urls in plugin settings setting the appropriate type.
I programmed this plugin for fun and do my best effort to support those that have issues with it, please return the favor and support me.