BEIJING: Teenage Russian figure skater Kamila Valieva starts her bid for a second gold medal on Tuesday at the Beijing Olympics, as anger mounts over the decision to allow her to compete despite failing a drugs test. The 15-year-old is at the centre of a raging controversy after the Court of Arbitration for Sport ruled on Monday that she could carry on at the Games even though she tested positive in December for the banned substance trimetazidine, which boosts endurance. It also put the spotlight once more on doping by Russian athletes, who are not allowed to take part at the Games under their…