Hi ounercat,
Through Canon USA support we only have information on products and software made by Canon, so we do not have information on if OBS could use two connected cameras at the same time. For information on OBS we would recommend contacting OBS support.
You can have multiple cameras connected in EOS Webcam Utility Pro. In EOS Webcam Utility Pro there will be an option for Scenes. You can set each camera as its own Scene. One thing to note with that is the software would only output the currently selected scene to your streaming or conferencing software. So you can have both cameras connected at the same time, but the EOS Webcam Utility would only output one of the camera feeds at a time.
