May I add a small bit of information on this subject? In Ireland, the origin of the name was generally "O'Mahony", pronounced "Mahany" or "Mahaney", with or without the 'O'. Spellings and pronunciations changed over the years in the United States and Canada, so Mahoney, Mahony, Mahany, Mahaney, and any variation with or without the 'O' could possibly be the same name. This was my mother's maiden name and I have experienced this both in the U. S. and on many visits to Ireland. Am currently looking for descendants of Eliza O'Mahony, emigrated late 19th century, to east coast of United States, married in Pittsburgh, had 3 sons, may have moved to Atlantic City, NJ and am having difficulty because of different versions of the name.