just looking at the wiring in our new house. The bathroom light fitting wiring currently features 2 lives tied together as well as 2 earths tied together. Neither combination is used with the actual light fitting. Can sort of understand this tying together in a "1-way" sense but am intrigued why they used the 2 neutrals for hooking up to the light fitting?
I'm no electrician but, from what I know about lighting wiring, one of the "neutrals" that you describe will actually be what is known as a "switched live" coming from your switch. From the way that you have described the fitting wiring one of the two lives that are coupled together will be the incoming live and the other one will go to the switch. The incoming neutral will go straight to the light fitting. If you look at the switch, you should find that one side of it has a live wire and the other side will appear to have a "neutral" wire coming off it. It is this apparent neutral wire that is actually the "switched live" feed that then goes to the light fitting. In this way there only needs to be one two core cable between the switch and the fitting, with the incoming mains remaining at the fitting junction box.