That's not exactly true. Tim Duncan was guaranteed 5,500,000 for the 2016/2017 season.
http://www.basketball-reference.com/con ... ayers.html (see number 142)
So it means that San Antonio is actually only paying him $893,750 for the 2016/2017 season, a far cry from the $6,393,750 largess they're claiming and the fact that they're using "Bird Rights" to do it means that money doesn't really count against their salary cap either.
http://basketball.about.com/od/collegeb ... rights.htm