I will note I have zero tolerance policy for multiple accounts created to evade bans or to deceive people.
Having said that I also realize people might have multiple accounts for other reasons like they forgot their password and just created a new one. If you have multiple accounts I can merge them, this procedure merges everything including post counts, old PM's, topic author etc. You will need to be able to prove the old account is yours, this is usually confirmed through the email address used with that account or the secret question/answer.
While on the topic if you have never filled out the secret question/answer I recommend that you do it. If you lose/forget your password and subsequently lose access to the email address the account was registered under there is no way to get it back. You can find this under the profile tab in the User control Panel.