Complex sentence: After first competing internationally in 2002, Stoner became MotoGP World Champion in 2007 for Ducati Corse and won a second world championship title in 2011 for Repsol Honda.
Split into simpler sentences: After first competing internationally in 2002, Stoner became MotoGP World Champion in 2007 for Ducati Corse. After his departure from Ducati to Honda following the 2010 season, Stoner won a second world championship title in 2011 for Repsol Honda.