Design patterns: data mapper + dependency injection?

I am following data mapper guide. But it has a model class in the mapper class. So I modified it by using dependency injection.

Model,

class User
{
    /**
     * @var int
     */
    protected $userId;

    /**
     * @var string
     */
    protected $username;

    /**
     * @var string
     */
    protected $email;

    /**
     * @param null $id
     * @param null $username
     * @param null $email
     */
    public function __construct($id = null, $username = null, $email = null)
    {
        $this->userId = $id;
        $this->username = $username;
        $this->email = $email;
    }

    /**
     * @return int
     */
    public function getUserId()
    {
        return $this->userId;
    }

    /**
     * @param int $userId
     */
    public function setUserID($userId)
    {
        $this->userId = $userId;
    }

    /**
     * @return string
     */
    public function getUsername()
    {
        return $this->username;
    }

    /**
     * @param string $username
     */
    public function setUsername($username)
    {
        $this->username = $username;
    }

    /**
     * @return string
     */
    public function getEmail()
    {
        return $this->email;
    }

    /**
     * @param string $email
     */
    public function setEmail($email)
    {
        $this->email = $email;
    }
}

Mapper,

class UserMapper
{
    public function __construct($model)
    {
        $this->model = $model;
    }

    public function findAll()
    {
        $resultSet = array(
            array('userid' => 1, 'username' => 'Odysseus', 'email' => 'Odysseus@ithaca.gr'),
            array('userid' => 2, 'username' => 'Penelope', 'email' => 'Penelope@ithaca.gr')
        );

        $entries   = array();

        foreach ($resultSet as $row) {
            $entries[] = $this->mapObject($row);
        }

        return $entries;
    }

    protected function mapObject(array $row)
    {
        $this->model->setUserID($row['userid']);
        $this->model->setUsername($row['username']);
        $this->model->setEmail($row['email']);

        return $this->model;
    }
}

Usage,

$model = new User();
$mapper = new UserMapper($model);
$users = $mapper->findAll();
print_r($users);

Result (which is incorrect),

Array
(
    [0] => User Object
        (
            [userId:protected] => 2
            [username:protected] => Penelope
            [email:protected] => Penelope@ithaca.gr
        )

    [1] => User Object
        (
            [userId:protected] => 2
            [username:protected] => Penelope
            [email:protected] => Penelope@ithaca.gr
        )

)

But it returns the correct result without dependency injection,

protected function mapObject(array $row)
{
    $entry = new User();
    $entry->setUserID($row['userid']);
    $entry->setUsername($row['username']);
    $entry->setEmail($row['email']);

    return $entry;
}

Result,

Array
(
    [0] => User Object
        (
            [userId:protected] => 1
            [username:protected] => Odysseus
            [email:protected] => Odysseus@ithaca.gr
        )

    [1] => User Object
        (
            [userId:protected] => 2
            [username:protected] => Penelope
            [email:protected] => Penelope@ithaca.gr
        )

)

So, how can I use dependency injection with data mapper to return the correct result? any ideas?