Lil Za -- Arrested Again ... for Vandalism in Jail

Justin Bieber's pal Lil Za pulled a double -- getting arrested for a SECOND TIME Tuesday ... while STILL under arrest, and it's all over a shattered phone ... TMZ has learned.

Sources tell us Za was minutes from posting bail and getting released from custody after getting busted for drug possession at Bieber's house this morning -- and then for some reason he flipped out and smashed a phone in the jailhouse.

We're told Za was almost immediately re-booked for vandalism.

Best of all, depending on the value of the phone ... this could also be a felony -- to go along with his felony drug bust.