Changing minecraft account name may unkowingly give Minecon 2011 cape

As can be seen in this video: https://www.youtube.com/watch?v=KCkQjyu3dAg a player changed their account name to "UsaOnBottom" and then noticed they had received a Minecon 2011 cape despite never having attended the event.

The current theory is that someone must have purchased a ticket and entered "UsaOnBottom" as the account name without such an account ever existing. Then when another person changed their name they instead got the cape.

There is no real way to test this bug, as you would need an account name that never has been used before but also was inputted while buying a Minecon 2011 ticket.

Note that it was not me who found this.