Zoom Video Tiles Changing

We had an issue recently, where everyone was in gallery view and the person who was speaking had their image suddenly appear in another persons tile.  In other words, the person who was speaking still had their tile open, but it started to also show up in someone else's tile later.  So the person speaking was suddenly showing up in two tiles at the same time.  The person who's tile was taken over by speaker indicated they could see this change, and the only thing they did on their end was to change the output volume and they think this could have caused the change.   Strange occurrence that happened twice with the same people?

Any ideas on what could have happened?

Thank you,