that's not how it works
if you rob a bank, serve your time and get out, then rob the same bank again, you're going to get convicted again
if you get convicted for attempt of murder, get out, and attempt to murder the same guy again, you're serving time again
the system is in place to prevent abuse of law, i.e. sending a person to court for the same crime over and over until he gets convicted
the situation that seems to be confusing you is that, in case when you get falsely convicted for murder, and the victim is actually alive, once you get out of prison you are theoretically free to kill him/her, as you'd already paid the price for committing the act
and I've never heard of such a thing outside of movies
also, fuck your shit, arnold is awesome