Page 204 on mine with the same warning, however there is no mention about the outward dimple to distinguish which nuts are which.
The odd thing with my disco is that when I purchased it, it was a one owner, 145,000 clicks with a full service history.
It was bog standard as if it had just left the showroom, so I doubt that the wheel nuts would have been changed.
And as I mentioned above, the only dimple nut on mine would have been the security nut replacement.
It would have been far more prudent for LR to have used a completely different thread for the spare so as the nuts could not be changed.

