SIDSTAR:
Just to clarify the AI position: Airbus changed the method of dealing with a locked out reverser last year but gave no reason for the change. Perhaps it was linked to the previous incidents?
In all likelihood, if the human factors reports on those incidents suggested that some pilots had a tendency to filter the information "both to idle, then one reverse" in such a way that only one lever was pulled back in some circumstances, then I expect it was down to that.