Summer McIntosh of Canada in action as she finishes the final to win gold and set a new Olympic record.

PARIS- - Canadian teenager Summer McIntosh claimed her second gold medal of the Paris Olympics on Thursday, winning the 200 metres butterfly with another extraordinary swim that washed away doping clouds that have hung over the La Defense Arena pool. Three days after a dominant win in the 400m individual medley, the 17-year-old delivered another clinical swim that oozed with teenage exuberance getting to the wall first in an Olympic record time of 2 minutes, 3.03 seconds. American Regan Smith had to settle for silver for the second consecutive Games, while China's Zhang Yufei took the bronze. With the win McIntosh becomes the first Canadian swimmer ever to claim multiple Olympic golds. Making the moment even more special, it came racing in what was her mother's best event. McIntosh's mom Jill Horstead was also a competitive swimmer and represented Canada at the 1984 Los Angeles Summer Games. "It's pretty cool tonight winning the 200 fly just because that was by far her main event," said McIntosh. "So sharing that moment with her is pretty cool. "I know she's just so proud of me along with the rest of my family." With the 200 individual medley and relays still to come McIntosh could yet add to her medal haul, which also includes a silver in the 400m freestyle on opening night. While the Canadian wunderkind is quickly turning into one of the Paris pool's star attractions, Zhang was getting nearly as much pre-race attention but for very different reasons. The first final of the night came with a mix of excitement and trepidation with the China swim team and their "Butterfly Queen" Zhang again under the doping microscope. A doping storm has followed China to Paris after the New York Times and German broadcaster ARD reported in April that 23 Chinese swimmers had tested positive for a banned heart medication but were allowed to swim at the Tokyo Games. Zhang was among those swimmers named in the report and went on to win the 200m butterfly in Tokyo. The World Anti-Doping Agency (WADA) has not named any of the swimmers. So impressive was McIntosh's swim that the doping discussion was effectively muted, although members of China's bronze medal winning 4x200m free relay team were later asked about the positive tests. "We will prove with our own strength that our results are absolutely clear and there is absolutely no problem," said Yang Junxuan, who swam the opening leg. "Our Chinese swimmers have (undergone) the most tests in the world, and we have been cooperating hard because we believe there will be a fair result." In the butterfly, Zhang was out quickly with McIntosh right on her tail for the first 100 before the Canadian shifted up a gear and the Chinese could not match her. As Zhang faded, Smith moved up to challenge but could also not catch McIntosh. "At the 1.25 mark, I feel like I hadn't even started trying to race it," said McIntosh. "I was really, really controlling it as much as possible. "Usually I kind of go out a bit faster, but I don't know, for whatever reason, I decided to kind of take it home as best as possible. "It worked out somehow."