Thank You, Discorde. This is a peculiar procedure indeed, calling for rather good understanding between the pilots. There must have been some reaction time between the P1s call for reverse and the response of P2, making the difference between a nice, smooth landing and ... well, something deserving to be called "arrival" rather than "landing".
At a risk of a thread drift, but thinking about it, I remember having heard of a similar SOP on the IL-62 with Interflug (although there not the P2, but the F/E pulled the reverse on the handling pilots request), occasionally raising the question of which one of the two was responsible for the impact that just occurred. Such "shared" operation of the flight controls seems to have been not uncommon a while ago.