A life sentence with more years added onto the life sentence is usually given to a prisoner to guarantee they'll never be set free from prison again.
It seems silly when you think about it but it really isn't after all.
When someone is usually given a life sentence with possibility of parole it means they have to serve 20 to 25 years before being eligible for parole.
So if they're given life with parole but the judge adds says another 50 or so years onto the sentence then the prisoner will have to serve a total of 70 to 75 years before parole can even be considered.
They could just as easily say life without parole but the laws are silly as it is.
Now if someone is given a life sentence without parole then they're just assuring that the prisoner is never getting out at all.
A prisoner has a chance to appeal a life sentence so the additional years such as 50 to 1,000 years or more added onto the life sentence is just insuring that the prisoner is never set free again.