And others can move to REV gate while still airborne on a long float. If the PM took over at that point one lever might remain latched to REV IDLE detent, until rectified by crew by resetting the REV paddle.
Does not explain the petals extended after the second landing, nor flying the GA with REV open.
Looks like some darn mechanical failure that was really not supposed to happen in a post-Lauda 767 world. (cometh forward, the Master of the combustion chamber?)