There are a couple areas on the ESB helmet at AoSW, which is the Empire hero, that were not present on the helmet when it appeared in ESB. However for the most, the additional marks are quite minor. The difference is that you are seeing the tour helmets at an extremely high resolution (dig cams), which they were never meant to be seen at or expected to look good for that matter.
Real props aren't pretty. They are often quite sloppy. They only need to look good enough to fool the camera. So what you see at MoM and AoSW are the helmets you saw in RoTJ and ESB, respectively. Keep in mind, as well, that the helmets are now over twenty years old. But I still think the helmets at the tour are not that much different than how they looked when they were first built.
