[Chris W]

you can try to register a double service into one house, but unless you have different names on different acccounts- eg joint tenancy with seperate flat numbers, you won't be able to.

If you have bought a cable modem from somewhere else then don't bother trying to register it because the person you have bought it off is selling goods that don't belong to him/ her and if you purchase then you could face charges of handling stolen goods.