@ziroAU Actually, when you change your username, your previous one is unavailable for other players to change to it for exactly 37 days. Those 7 days are when you can change it back. As long as you don't pass the 37-day mark, no one will take your IGN.
I think that if you change your IGN to a whole different one, and THEN changing it back with the capitalization change, it might work. I did this exactly and am waiting for the result. I will update this comment when I try it.
@ziroAU Actually, when you change your username, your previous one is unavailable for other players to change to it for exactly 37 days. Those 7 days are when you can change it back. As long as you don't pass the 37-day mark, no one will take your IGN.