I could not concur more strongly with Tsunamy in regards to this concern. Personally, I would like to see Legislator applications ask an individual's previous regional affiliations (or at least the important ones), any previous identities they may have been under, and names they generally go by in Nationstates.

As for how to close the exploitation further, I would say either classify failure to disclose previous aliases as identity fraud under the Criminal Code, or add a new provision recognizing such a malicious failure to disclose as a crime of Citizenship Fraud (though with a new name, as this is for Legislator not Citizen). I think classifying it under identity fraud might be the best way?