I remember also once asking someone to change their avatar because they had the same as me, and I felt it was 'mine' since I've had it forever... They were very cooperative

I think it's a bit like in hockey teams - if there is a player with number #22 and then a new player joins the team, who's played with #22 before, they have to come up with a new number. Not quite the same but in principle that's what it is about methinks...