We'll be sure to keep an eye out for them. If they are doing anything extremely offensive, you can be sure that they won't be doing it for very long.
One way you might address this is by changing your name around a bit. Not completely - but perhaps add an alt-code or two to make yourself stand out and so that everyone knows you are someone different. Something like that would really be your choice to do.
Fear not though, if they are deliberately impostering you, most players like that get bored and find something else to occupy their time.