There’s only 1 Staffordstown in Co Antrim. It’s a townland of 169 acres just west of Randalstown. There were no Russell households in Staffordstown by the 1901 census, nor listed in Griffiths Valuation for 1862 (though it did not show every household the way the census did). Do you know what denomination the family were?
http://www.census.nationalarchives.ie/pages/1901/Antrim/Cran...Can’t see a townland of Dunnamaugh listed for Tyrone. Dunnamanagh perhaps?