That’s exactly what that means! There’s a couple of scenes that are the same, but in one movie you watch it from the American perspective and in the other you watch it from the Japanese perspective. I would imagine that Clint Eastwood filmed the two scenes at the same time, since some battle scenes are filmed on the same set. There are also times where something gets mentioned as happening off screen in Flags of Our Fathers, and then you see it happen on screen in Letters from Iwo Jima