A court condemned them to up to 40 years in jail each for the murdering of 17-year-old Kian Delos Santos in 2017.
President Duterte launched the anti-narcotics campaign in 2016, to deal with a rampant drug problem.
Since then 5,000 dealers or users have been killed, according to police.
President Duterte has been criticised by human rights groups for what is seen as sanctioning the extrajudicial killings and promising to pardon police officers convicted for "drug war" killings.
"A shoot first, think later attitude can never be countenanced in a civilised society," said Thursday's ruling by Judge Roldolfo Azucena.
"Never has homicide or murder been a function of law enforcement. The public peace is never predicated on the cost of human life," he added.