Make multiple accounts with different emails and passwords and make their display name something like yours, with a few letters tweaked. This way, the imposter would not be able to find an available name that looks similar to yours and so he will not be able to make any imposters.
For this one, you need a membership. The way you do it is that you visit Xuan's shop and purchase a Title for your name, for example, Sir/Lady. By doing this, you will make it easier for the betters to know its you and any imposter would be spotted fast because they would have no title besides their name.