Early in the game, when you're walking with Wheatley (holding him, I think), you pass by a turret on a stopped conveyor belt. Wheatley reacts unusually, urging "don't make eye contact" and the like. The turret itself mumbles something, says "thanks anyway," and then says (in a really sad voice) "I'm different."
Later on, after you escape from GLaDOS with Wheatley, you come by the "redemption" line, where broken turrets are sent into an incinerator (a sort of heaven I suppose). However, there's one intact turret on the belt, and it says (in a really sad voice, this time almost making me tear up) "I'm different."
Is this the same turret as the first one? Is there some backstory to this turret?