Remember, quite a lot of people would like to put their own name or a common or popular name as their nickname - a good example being 'Alex':
A previous example of repeated names used to be blade19899 - see here - a lot of which seemed to be copying this user:
Also, being able to put the same name means you don't get what you get with many other sites - Alex01, Alex-2, etc - which can if anything be more confusing...