In any society or social grouping, a person develops a reputation that he or she must live with. The human desire to be liked and accepted is one of the primary drivers in leading people to behave in socially acceptable ways. Anonymity is desired when one wants to do something unpopular without suffering the recourse. Bulletin boards by their very nature are fairly anonymous to begin with. Alter egos and second handles serve only to allow people to behave in ways that they do not want known by the greater group and in darn near all instances, that is a detriment rather than a benefit to the community as a whole. We can never stop all such occurrences as many people (in a way I just cannot understand) seem to draw some type of satisfaction from annoying others and actively work to do just that. But we should continue to strive to make these occurrences as rare as possible.
Gleff again has good points around lost passwords or a change in handles. With a community this large we should provide tools to allow self-service to those with password issues if at all possible. I am not certain what tools exist there today. And, especially for new users, we do want to allow a change in handle. Your handle is your identity on these boards and sometimes that perfect witty name comes to you right after you register.
Allow creativity but prevent abuse. Who could possibly be against that? The devil again will be in the details. And sometimes you are better off maintaining policies that are slightly vague and permit a degree of human judgment. Those who seek to abuse and annoy are often outstanding at using the rules to their advantage and playing their games just within the letter of the law. There is an advantage to having someone who can make a determination based on the spirit of the rules. I haven't been around as long as some, but that is exactly what I believe we currently have. While there might be some bumps in the road as we ramble through the process, I haven't heard anyone yet complain of a complete failure to eventually reach the right result. That to me means that we might look to tweak things around the edges, but for now anyway, the current policy seems to be working.