A 49-year-old man fatally slashed his girlfriend and an associate in the neck before being found with self-inflicted injuries on a houseboat, a court heard.
Lee Peacock is accused of fatally slashing his partner Sharon Pickles and a second alleged victim, Clinton Ashmore, at separate central London addresses, hours apart, last month.
Peacock is later said to have self-harmed after being tracked by police to a houseboat on Grand Union Canal, and was taken to hospital.
He entered no pleas to two counts of murder during a 15-minute hearing at the Old Bailey on Wednesday.
Peacock, of Harrow Road, west London, appeared via videolink from HMP Thameside and spoke only to confirm his name and date of birth.
He was further remanded in custody and will appear next at the Old Bailey for a plea hearing on November 12.
The charges came after officers went to a property in Ashbridge Street at 9.30pm on August 19, when concerns were raised for the welfare of those inside.
Police found Ms Pickles, 45, who was pronounced dead at the scene.
A few hours later, at 2.15am on August 20, officers were called by London Ambulance Service to a second property in Jerome Crescent, around half a mile away, where they found Mr Ashmore, 59, who was also pronounced dead at the scene.