Gillian Phillips, 54, and David Oakes, 60, had more than 40 stab wounds each when police found them at her home in Stansted Mountfitchet, Essex, in 2015.
Chelmsford Crown Court heard Brett Rogers was jailed in 2012 for breaking his father's eye socket.
The 23-year-old, who received a life term, had denied two counts of murder.
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Jurors heard Rogers was found at his mother's home in Bentfield Gardens after the attacks laughing and covered in blood.
Mrs Phillips had been stabbed at least 41 times in the head, neck and torso. Mr Oakes suffered 56 wounds to his head, face and neck and died of severe head injuries.
Judge Philippa Whipple said it was a "brutal and sustained attack".
She said: "One image that will stay in the mind of anyone involved in this case is that of the reconstruction of your mother's face showing the stamp injury attributed to your shoe on her left cheek.
"You are a man who attacked the people who loved you the most.
"Look at what you have done to them.
"By your actions you have ruined your family's life and you have ruined your life."
A forensic scientist told the court seven knives found at the scene had been examined, many of them with Rogers' DNA on the handles, along with that of Mrs Phillips and Mr Oakes.
Rogers claimed the pair were attacked by a mystery stranger while he went out to the supermarket for five minutes.
Mr Oakes, 60, had recently undergone treatment for cancer. He was stamped on while he was on the ground and had cuts on his hands and knuckles where he had tried to defend himself. He died the next day.
Rogers was given a 32-year minimum term. If ever released, he will be on licence for the rest of his life.
The court heard he was on licence at the time of the killings, after leaving his father with a broken eye socket in 2012.
A man has been jailed for at least 32 years for stabbing his mother and her friend to death while he was on licence after attacking his father.