You’re ignoring that the state should rectify unacceptable situations. With wrongful imprisonment, the state can rectify the situation and compensate the innocent. With the death penalty, this is never possible. And even if such a rectification is not done, at least the prisoner was still able to live somewhat of a life.
This makes life imprisonment infintely more acceptable that the death penalty. There’s no doublethink in admitting there are different gradations of unacceptable.