Hi Reiver,
I think it'll mean that the surveyed stone would only have the name and the year inscribed.
Possibly on the top or on the back, it would also have something like 'Holds 2 Lairs' - meaning that there was 2 burials, or the space for two burials OR that the same person owned two lairs side by side.
The only way to confirm this would be if you were able to access any existing Lair Records, if there are any.
Anne