Aaron Jamie Ball, 34, who suffered from paranoid schizophrenia and believed he was either a clone of Hitler or his grandson, pleaded guilty to two charges of defensive homicide and one charge of causing serious injury recklessly.

Raymond McCombe, 38, died from 34 stab wounds, Toby Lynch, 25, died from a stab wound to the chest, and Steven Mark, now 31, was seriously injured but survived after being stabbed three times.

Supreme Court Justice Elizabeth Curtain said Ball had been living in a house in Miller Street, Casterton, with his mother, Dianne Hutchins, and sister, Chantel Hutchins, when he stabbed the three men.

"You and your family were in the habit of yelling abuse at neighbours and passers-by and, indeed, filming them with your phones," the judge said when jailing Ball on Wednesday for 20 years with a non-parole period of 17 years.

"You were also in the habit of taunting and then chasing children away, which in turn caused disputes with their parents and other adults, and so it was that you and your family became known as 'the loonies'.

"At around the time you moved to Miller Street (in 2009), you distributed an unsigned letter to nearby residents, warning them that you had a violent temper, which was difficult to control. You claimed to be trained in weapon techniques and you warned people to leave you and your family alone."

Ball, who had a limited intellect and suffered from delusional beliefs similar to his mother (who has since died) and sister, stabbed the three men during a neighbourhood dispute on October 4, 2011.

Justice Curtain said that according to a psychiatrist, Ball continued to express "a well-systemised set of conspiracies involving missing persons, homicide and the involvement of police and the victims of these offences".

"You continued to hold bizarre ideas, for example, being a clone or grandson of Hitler, being able to read minds and having been subject to experimental medical procedures.

"It appears the genesis of these ideas derived largely from your mother's beliefs."

The judge said she accepted that the three men came on to Ball's property "in circumstances where there had been a lot of yelling, and mutual abuse, and where your comments and those of your mother referencing Raymond McCombe's deceased wife were inappropriate and no doubt inflammatory".

"I accept also that alcohol had been consumed, it was night time, it was dark, and clearly this must have been a dynamic, fluid and highly-charged event, and it was in those circumstances that you responded to what you believed was a threat to your life or to the threat of being seriously injured and you produced the knife ... and went on to stab Toby Lynch, Steven Mark and Raymond McCombe.

"True it is that three men came onto your property, but they came unarmed, and Steven Mark expressly said he had not come to fight you.

"The reality is, your response to the threat as you believed it to be was totally disproportionate to the conduct and menace posed by those three men, and that belief in the necessity of your actions, although genuinely held, was unreasonable in all the circumstances."

Ball was originally charged with two counts of murder and one count of attempted murder but on the day his trial was due to begin the Crown accepted his guilty pleas to two charges of defensive homicide and one charge of recklessly causing serious injury.