The target coordinates were not for the roof but much below on the floor of the building. When the bombs are released by a formation of aircraft, they will follow exactly same profile and trajectory to the target to hit the point on ground. BUT the vertical entry point of each bomb will be a bit different based on the distance from the target. The bomb released farthrest from the target will enter the roof at an angle which will be less steep than the bomb fired from a distance comparatively closer to the target. These multiple trajectories will enter the roof with that much separation between them as their vertical descent angle. Here the roof itself was also sloping. That caused the difference between the entry points of the bombs.