It seems hard to believe that this was possible. I would think that a person working on something that was require to be de-energized in order to do the work would have a positive way of knowing it was de-energized and a way to prevent it from becoming energized before the person doing the work was finished and in the clear.
The question is first, is that possible on the equipment in question (some older equipment may not be suitably equipped for the practice), and second, if the capability did exist, was it in use…