There happen ( by chance ) to be two addresses sharing a number and postcode there in the first 50 addresses, but that's the least of the problems for a scheme using no + postcode as a unique id I'm afraid!
Try HD7 4PD to get "1 Moles Head, Golcar, HUDDERSFIELD, HD7 4PD" and "1 Prospect Place, Golcar, HUDDERSFIELD, HD7 4PD"
Try HD4 6XA and see "1 Broad Lane, Thurstonland, HUDDERSFIELD, HD4 6XA", "1 Blake House Thurstonland, HUDDERSFIELD, HD4 6XA", "1 Clough Cottages Thurstonland, HUDDERSFIELD, HD4 6XA", "1-2 Clough Cottages Greenside Road, Thurstonland, HUDDERSFIELD, HD4 6XA"
And of course there's the other direction: EC1N 8QX covers a bunch of flats in the same building, so one postcode includes "Flat G.7, Ziggurat Building, 60-66 Saffron Hill, LONDON, EC1N 8QX" and "Flat 1.1, Ziggurat Building, 60-66 Saffron Hill, LONDON, EC1N 8QX" - in other words, multiple properties have the same number within the street, and the same latitude and longitude. Also the building "number" has a hyphen, the flat "number" has a dot and can have a letter, and the building has a name too.
It would be nice if it was a unique identifier, but the uk postcode is not, even combined with part of an address like 10, or even 10 high street, sometimes the village is also required to narrow it down. This might have worked for you on a limited set of data, but the assumptions are not valid across the uk.
This seems unlikely. In a small village people know the other house names enough to avoid a collision - in England I've a feeling Parish Councils used to keep order in this regard.
This page suggests that Local Authories legislate (bylaws I guess) on the allowed names: http://www.housenameheritage.com/hnh_extras_officialviewlong....
Quoting that link:
>"The Local Authority will liaise with the Royal Mail to ensure there is no conflict with names of other properties in the same street or immediate area, before formally registering the name. If there is a problem, an alternative name must be submitted. In some cases, the Local Authority may explore the possibility of a house number being registered at this point, in addition to (or instead of) the new name. Once the change has been approved, the Local Authority will normally advise relevant bodies such as the emergency services. The same procedure applies for brand new properties which, for whatever reason, cannot be numbered (however, virtually all new properties today are numbered)." //