Kenneth Patrick Mahoney, 52, pleaded guilty to manslaughter after he hit David Tweedly twice on a St Kilda street in October 2017.

He attacked Mr Tweedly after a "perceived slight" and hit him twice for no reason, Justice John Champion said during his sentencing remarks in the Supreme Court.

The second "haymaker" punch knocked Mr Tweedly to the ground and Mahoney threw his arms up in an "apparent celebration", Justice Champion said on Wednesday.

The victim managed to get up after the attack, make his way to a chemist before returning to his room at a boarding house.

Mr Tweedly called an ambulance but after speaking to paramedics decided not to go to hospital with them and returned to his room.

His family called in the police when he didn't show for his 50th birthday party at his sister's house on October 20.

Mr Tweedly's body was found on his bed two days later with a note next to him that read: "a guy called Ken who had just done 10 years gaol kicked the door".

An autopsy could not pinpoint his time of death but found he died of a head injury.

His family members struggled to come to terms with their loss and described him as a "quiet, loving and placid" man who loved playing the guitar.

Mr Tweedly's sister Vanessa said her heart breaks knowing he died "alone and scared".

Mahoney had been released from jail in January after spending nine years behind bars for the manslaughter of his partner.

"You now find yourself in the tragic and unusual situation of being sentenced for the offence of manslaughter a second time," Justice Champion said.

He noted it was the first time it had happened in Victoria.

Both attacks happened while Mahoney was heavily intoxicated, Justice Champion said.

"They were committed in different circumstances upon very different people, but both were involving violent killing with your own hands."

The judge took into account his guilty plea, "bleak" chances of rehabilitation, remorse and the protection of the community.

Mahoney was jailed for 11 years with a non-parole period of eight for the fatal attack.

Australian Associated Press