(I can't resist mentioning that my solo went better than his did.)
Which is the root of the conflict created when two characters have a similarity.
Ever notice how in some stories, a bully or love interest or rival is formed with the Protag and it doesn't seem to make sense outside of the idea that they were magicly drawn to him/her?
Being of the same country in a foriegn land can keep two people talking to each other, even if not the same region! (How about them Giants?)
In Harry Potter (which come up first because there are so many kids) Harry crushes on girls that also love his sport, anyone that reminds him of his bulling cousin automaticlly annoys him (which provided a nice amount of dissonance when he discovered his father had been a bully) and things like inheirited appearances can make or break your relationship with others: If Harry had looked like his mother I doubt Snape would have hated him as much! :P
Repeating looks, attitudes, behaviors and the like allows even the noblest characters to prejudge as humans do. It also explains why peolpe bother to be friends with, love, admire or plain pay attention to the Protag without resorting to lazy Author Gravitation.