Each unique email address can only have one account assigned to it. So the only way you can have more than one account is if you used two or more different email addresses.
You can check if there are accounts associated with multiple email addresses by going to https://www.faxbetter.com/Application/Secure/ForgotPassword.aspx and entering each of your email addresses. If the email address you entered is associated with an account, we will email the password for that account to the associated email address. If an account is not associated with that email address, you will be informed as such.