According to Official Guinness Records,
The greatest distance between two rounds of golf played on the same day is 15,982 km (9,931 miles) by John Knobel (Australia) who played two full 18-hole rounds, firstly, at The Coast Golf Club, Sydney, Australia, and then Forest Park Golf Club, Woodhaven, New York, USA, on 21 May 2006.
For a complete list of 2006 records, please visit 2006 Guinness Records in United States.