I don't see why two couldn't share a whole tea service if sharing is allowed....the actual amount of tea in a pot was about four (albiet small china cups) for me, so two could share one pot of tea, but you would only have a couple of cups each....I saw people sharing POTS of tea, but no one sharing a whole tea, although I did see some people ordering a whole "Buckingham" and the person with them ordered a cheese plate and the two shared both.
If you do share, I highly suggest ordering an extra scone because you only get one and half of a scone is not enough, they are too good!!