http://zend-framework-community.634137.n4.nabble.com/using-of-two-auth-in-zend-td2244059.html

Admin_IndexController.php

<?php //file: application/modules/admin/controllers/IndexController.php

class Admin_IndexController extends Zend_Controller_Admin
{
    public function init()
    {
        $request = $this->getRequest();
        $auth    = App_Auth_Admin::getInstance();

        if (!$auth->hasIdentity() && ('login' !== $request->getActionName())) {
            $this->_helper->getHelper('Redirector')
                          ->gotoSimple('index', 'login', 'admin');
        }
    }


    // ...
}

App_Auth.php

<?php //file: library/App/Auth.php


class App_Auth extends Zend_Auth
{
    protected function __construct()
    {
        $this->setStorage(new Zend_Auth_Storage_Session(getclass($this)));
    }
}

App_Auth_Admin.php

<?php //file: library/App/Auth/Admin.php


class App_Auth_Admin extends App_Auth
{}

App_Auth_User.php

<?php //file: library/App/Auth/User.php


class App_Auth_User extends App_Auth
{}