Complex sentence: His son, Rick Mackey, became the only legacy winner when he also won in 1983, Dick Mackey's son, Lance Mackey is now racing in the Iditarod 2007.
Split into simpler sentences: His son, Rick Mackey, became the only legacy winner when he also won in 1983. His other son, Lance Mackey is now racing in the Iditarod 2007.