Answer
In addition to John McEnroe, Stefan Edberg also achieved a No.1 ranking in both singles and doubles, although at different times. He was the top-ranked singles player in the world for a total of 72 weeks, including a 19-week run at the top in 1990. He was also the top-ranked doubles player in the world for a total of 23 weeks, including a 10-week run at the top in 1991.