The killing brought to six the number of people slain by the extremist group in the Sulu capital in just four days.
The casualties included four Marines, who were shot dead while the military was observing a suspension of military operations due to the visit of an Organization of Islamic Conference group to the island-province.
Capt. Jose Richie Pabilonia, information chief of the Armed Forces Southern Command, said two Abu Sayyaf hit men first felled Jurick Pollalos, 22, at about 5:20 a.m. at the New Oriental Coffee Shop where he worked.
About 25 minutes later, another civilian, Ruel Bernal, 32, was gunned down.
"The killings of these innocent civilians are believed to be the handiwork of the urban terror group operating in Jolo," Pabilonia said.
The military believes that the assassins were new Abu Sayyaf recruits on test missions.