JoEhJoEh, I have no pictures of my neighbors, above or below. Most people's avatars are chosen by the user themselves and the vast majority are unique to that user.
new users will have a basic, default avatar until they choose one of their own. It will be the uppercase first letter of your username. For example, mine would be an "M". Yours would be a "J". So in that case, two "neighbor" posters could theoretically have identical pictures but that rarely happens.
and even if it does, it's really nothing to worry about. Everything is going to be okay.