Not quite sure what has happened here Duncan, will have a chat with the local build engineer to see how they have wired these and get back to you, ideally both are wired back to a single point somewhere but looks like this may be non standard. Some developers still use Siamese internally which is a bit pointless now (more difficult to install as well).
Don't worry though, none of this will make a huge difference to your install. Will drop by site myself sometime if needs be to make sure that everything goes OK for you.
Will keep you posted on the fibre work