Hi Hanson,
Users are not allowed to login until the email is verified if you have email verification enabled.
If a user tries to login and their email is not confirmed it will resend the confirmation in case it was not received. So this could happen if the user keeps trying 20 times to login and never clicks the link in the email message to verify their email address.
It seems like unusual behavior for a user to do that unless he has not received the confirmation email, sending email does not guarantee it is received, you may want to check if they receive it or not.
That is a very old version of mojoPortal, you may want to consider upgrading.
See Upgrading From Previous Versions for notes about upgrading.
Hope it helps,
Joe