As I wrote before, it is not easy for one perp to kill 2 people in the same room because other one would wake up and try to help, scream, or started running for help. Others would wake up for sure. And he had to do it twice, two rooms two people. If there were 2 or more perps, it would be easier, faster and quieter. IMO
If he goes ear to ear on the first, then stabs the 2nd one. There's no chance. Especially if they are in the same bed.
This guy has probably played it over and over in his mind.