IIRC in the Farewell Shinsengumi arc Hijikata and Kondo attack Oboro and it seems they killed him. Later we see Oboro alive, which would make you assume he wasnt dead but wounded, but later Utsuro when he sees Oboro coughing blood tells him that if he keeps dying (or something like that) even he would die. Did Kondo and Hijikata kill Oboro and he resurrected kinda like Utusuro did when Gintoki chopped his head, or was Oboro just wounded and he never died of Hijikata and Kondo attack?
The fight you mention happens in episode 315. Hijikata slashes at Oboro's lower right abdomen and Kondo cuts at his left arm, and we see Oboro fall down. These are not necessarily fatal wounds, plus if you add the fact the Oboro has some of Utsuro's immortal blood inside him, it's actually probable that Oboro survived after that fight. He only dies later on in his final fight with Takasugi.