There is currently no way to join multiple breakout rooms at the same time. I tried running Zoom as different user on Windows but that gave me an error. The business version allows you join multiple meeting simultaneously, but not the same meeting multiple times. There really should be some way to do this. I cant use the web browser version because I need to let my client’s access my screen from multiple breakout rooms. Sounds like a pretty basic feature that is not too difficult to implement (I think), but can give many users, especially teachers, a much better experience. I would definitely consider upgrading my account if this feature was there.