Why not remove the reference to the original birth record from the index?
Indexes to birth records are provided and made publicly available under statute. They are kept in large bound paper volumes in the Family Record Centre in London and in local register offices, as well as on microfiche in libraries etc across the country. It would be impossible to remove the reference to the original birth registration in all copies of the indexes. Any attempt to delete the entries would only serve to highlight them. No other references to records which have been re-registered are removed.