I apologise if I have misread all of the posts, but I think you may have the wrong end of the stick so to speak regarding ip address duplication.
It is entirely possible for multiple websites to have the same ip address. In this instance they would all be running on the same server, it all works by using the host headers sent by your browser (or virtual hosts in the apache world). I don't believe they are duplicating ip addresses, if they did the results would be totally unpredictable eg you could visit one website but get another depending on which server responded first etc.
Apologies if you are already aware and I misunderstood all the posts, but I thought it best to point that out before complaints were raised.
Regards...
T