During the first attack on October 31, 2017, Nuku approached another prisoner from behind with a large metal shank.
He used this to strike the victim to the head, causing five lacerations.
When asked to explain his actions, Nuku said he committed the offence as the victim had falsely claimed he had taken his CD player.
Less than a month later, Nuku approached another prisoner from behind and stabbed him repeatedly with a metal shank.
He stabbed the victim not fewer than 12 times. Nuku said the attack took place after the victim had taken his biscuits.
Justice Matthew Downs said both offences, along with Nuku's first- and second-strike offences, all exhibited very serious violence.
Nuku's first-strike offence, in July 2015, involved him wounding another prisoner by breaking his arm and trying to break his other limbs.
He then committed his second-strike offences in October 2016 by attacking, with others, prison guards with weapons.
Justice Downs said there were six things that made Nuku's offending worse.
"First, each offence involved very serious violence. Second, each was premeditated and in retribution for a trivial wrong.
"Third, you used weapons: a sharpened shank. Fourth, you specifically attacked the head, including by stabbing behind the ear.
"Fifth, you continued with the second attack after another assailant joined in. Sixth, you
committed both offences in prison while there for very similar offending."
Justice Downs said Nuku's offending was near to the most serious of cases governed by the offence of wounding with intent to injure and he had little, if any, empathy for his victims.
He said Nuku poses a high risk of reoffending in prison and beyond.
"You pose a high risk of reoffending. Your offending is escalating. You show little inclination for reform. This despite receiving two long prison sentences only recently.
"Plainly, you are dangerous. You seem to take pride in that. An exceptional sentencing response is now required," Justice Downs said
Nuku has a long history of violence, beginning at age 16. He has 68 convictions and five Youth Court notations, 17 of which are for violence.
He was a member of the Mongrel Mob, but is now affiliated with the Killer Beez.
Justice Downs said Nuku had wanted to be a "lifer" since the age of 18 and admired prisoners who frightened other prisoners and guards.
Nuku had also been excluded from alcohol and drug treatment programmes because he failed to comply with the rules and had not been willing to address his use of "dope".
Justice Downs told Nuku, his future was now in his hands.
"Preventive detention is the only sentence that may persuade you to take responsibility for your actions, and in turn encourage reform.
"Preventive detention may help you come to appreciate violence is not a sustainable way of life, and destructive only, both for your victims and you."
