The victims, Shubham Pandey and Prachi, who were in their 20s, were on their way back home on a bike when a speeding Honda Mobilio car hit them from behind, the police said.
The impact of the accident was such that both the victims were thrown in the air and fell off from the flyover, it said.
Both of them suffered severe head injuries. While Pandey died on the spot, Prachi succumbed to injuries in the hospital.
The accused driver, Mohammad Anwar, was caught by locals and handed over to the police who said the car was being driven at a high speed.
The vehicles have been seized, the police said.