aMember (site.php): disallow signups with same first and last name (usually spam signups)

site.php

<?php

Am_Di::getInstance()->hook->add(Am_Event::VALIDATE_SAVED_FORM, function (Am_Event_ValidateSavedForm $event) {
    $form = $event->getForm();
    $vars = $form->getValue();
    if (isset($vars['name_f']) && isset($vars['name_l']) && $vars['name_f'] == $vars['name_l'])
    {
        $event->addError('Some Error Occurred! Please try to signup later...');
    }
});