I normally make reservations for two people, even if it s likely that I will end up traveling alone. Although I have never brought someone into a lounge that wasn't staying in my room, I doubt anyone would have questioned me if I had done so. Some locations charge extra for a 2nd guest, so adding a 2nd unnamed person to a reservation may not make sense.

There have been instances where someone with lounge access will bring different people into the lounge during their stay. Although there may be only two "guests" in the lounge per room, every friend or family member ends up utilizing the lounge. The above policy may be intended to stop that form of abuse.