If the dropped one has a tiny crack in the tube (losing vacuum extremely slowly, perhaps) or some other tube damage, and the smoky one has a faulty analog board, then combining the two might give you a better display. This assumes you have one good tube and one good analog board in total. If you have one good tube, but both analog boards have problems, you might negate some of the problems, but not all of them.
If there is a tiny tube crack, then the life of that display is obviously limited.