The Iron Range Research Center at http://www.us-census.org/states/minnesota/s-mn.htm#Stearns is supposed to have all the naturalization records that have been put on microfilm. They list 2 Hugh Murphys and one Margaret (Mrs. Hugh R. Murphy). Perhaps those are the two documents that you already have. If there are other ones you might have to go to Stearns County and do a search. Nancy Pundsack