The most common explanation is that you registered up twice for our site; you may have meant to update your e-mail address and signed up again by mistake, or you signed up as a new user from a different computer, without remembering that you already had an account with us under your old e-mail address.
If you have two accounts, one under your old e-mail address and another under the new one, you can simply log out from the first one and log in again using the second one.
To logout, click on the following link, or cut/paste it into a new browser window:
Then you can login again using your new e-mail address here:
If you don't remember the password, you can reset it by going to our Forgotten Password page. Remember to enter your new/current valid e-mail address!