Spectators at the artistic swimming in Hangzhou might have thought they were seeing double as the 26-year-old siblings from China won duet gold following the free routine.
"This competition is important for the qualification for the Paris Olympics," Qianyi said.
"For the Tokyo Olympics (in 2021) I went with the team. This time my sister and I represented the Chinese team in the duet.
"My goal is to stand on the Olympic stage with my sister."
The Games wrap up on Sunday.