Complex sentence: He set two world records at the 2004 Paralympic Games in the 100m freestyle and 100m butterfly events; he received a gold medal in the former event, for which he received a Medal of the Order of Australia.
Split into simpler sentences: He set two world records at the 2004 Paralympic Games. They were in the 100m freestyle and 100m butterfly events, events where he also received gold medals, for which he received a Medal of the Order of Australia.