I seem to have done it>
I removed this line:
if (empty($data['email2'])) {
$errors['email2'] = get_string('missingemail');
} else if ($data['email2'] != $data['email']) {
$errors['email2'] = get_string('invalidemail');
}
And commented out:
// $mform->addElement('text', 'email2', get_string('emailagain'), 'maxlength="100" size="25"');
// $mform->setType('email2', PARAM_NOTAGS);
// $mform->addRule('email2', get_string('missingemail'), 'required', null, 'server');
Now it's more user friendly.