Elevation doesn’t matter to Strava when it comes to matching up segments. They just care that the GPS coordinates (like, the maps as seen from above) overlay each other within a certain margin of error.
The Cauberg basically lays on top of the start of Norton Summit, as seen from above. So if you ride Norton Summit in France, it’ll also give you credit for the Cauberg segment in France. (Or the same goes for Watopia.)
The simple solution, I think, is for Zwift to just put a slight turn into the start of the Norton Summit or Cauberg climbs. Then the roads won’t line up. They’ll need to check this on an ongoing basis, though, so future climbs don’t overlay on each other. Really only applies to super short climbs…