There was both an audio and a visual indication of DUAL INPUT (light on the panel + "dual input" announced verbally). The co-pilot commanded priority take-over (from the pilot, who had just second previously done the same) without announcing it. This would have been clear if they looked at the panel that shows which side has priority, but in that confusion, their attention would've been elsewhere (airspeed and bank angle mostly).

Source (in French): https://www.vanityfair.fr/actualites/articles/vol-af-447-rio...