Bonar Stewart Bain ( February 4 , 1923 -- February 18 , 2005 ) was a Canadian actor and the identical twin brother of actor Conrad Bain , who starred in the television sitcom `` Diff ` rent Strokes '' as Phillip Drummond and `` Maude '' as Arthur Harmon .
Bonar Stewart Bain ( born February 4 , 1923 -- February 18 , 2005 ) was a Canadian actor . He was the identical twin brother of actor Conrad Bain , who starred in Diff ` rent Strokes as Phillip Drummond .