I doubt it's true except in perhaps a rogue department. That stuff did happen sometimes. HR would never let a practice like that fly formally though. Amazon's HR is ruthlessly strict about curtailing legal risk.
I've been gone for most of the company's life at this point but I sat on several hiring committees and changed jobs sometimes as often as every six months so was interviewer as often as interviewed and a staged office fight never happened in front of me. Though I can also see it as being an excuse to cover a real fight, which did happen in front of me more than once. "Oh, no, the VP and product manager don't really hate each other... The office is... fun, really! Low stress. Work life balance... It was a test! Yeah, that's the ticket."