If the same user want to change the username back, it is allowed.
I have found a weird bug with this add on. I have a dedicated forum turned on for the name changes, and my user ID is specified as the person who makes the post. The problem is after that post is made, I am shown as someone who is sharing Ip with the user that did the name change. So if 'apple' wants to change to 'orange', and I am 'admin' whose userid is being used to post the thread, then admin has the same shared IPs as orange. And vice versa.