Fonksiyon neden birden fazla döner ?

    public function sendNotification(){
        
        $this->pageTitle = 'Ödeme Bildirimi';

        if($_POST['sendNotification']){
            
            $senderName = $_POST['senderName'];
            $senderUserName = $_POST['senderUserName'];
            $payment = $_POST['payment'];
            $bank = $_POST['bank'];
            $total = $_POST['total'];
            $date = $_POST['date'];
            $message = $_POST['message'];
            $ip = $_SERVER['REMOTE_ADDR'];
            $userAgent = $_SERVER['HTTP_USER_AGENT'];
            $senderID = $_SESSION['id'];
            
            $sql = $this->database->query("INSERT INTO notification (sender_id, name, user_name, payment, bank, total, date, message, ip, user_agent) VALUES ('$senderID','$senderName','$senderUserName','$payment','$bank','$total','$date','$message','$ip','$userAgent')");
            if($sql){
                return 'Ödeme Bildirimi Gönderildi';
            }
            
        }
        
        $paymentValue = array("Havale & EFT", "ATM");
        $bankValue = array("Garanti", "HSBC");

        $val = '
            <br /><br />
            <form method="POST">
                <table align="center" cellpadding="10" cellspacing="5">
                    <tr><td>Ad Soyad</td> <td><input name="senderName" type="text" value="'. $_SESSION['name'] .'" readonly="readonly" /></td></tr>
                    <tr><td>Kullanıcı Adı</td> <td><input name="senderUserName" type="text" value="'. $_SESSION['userName'] .'" /></td></tr>
                    <tr><td>Ödeme Türü :</td> <td>
                        <select name="payment">
                            <option value="'. $paymentValue[0] .'">'. $paymentValue[0] .'</option>
                            <option value="'. $paymentValue[1] .'">'. $paymentValue[1] .'</option>
                        </select>
                    </td></tr>
                    <tr><td>Banka :</td> <td>
                        <select name="bank">
                            <option value="'. $bankValue[0] .'">'. $bankValue[0] .'</option>
                            <option value="'. $bankValue[1] .'">'. $bankValue[1] .'</option>
                        </select>
                    </td></tr>
                    <tr><td>Miktar</td> <td><input name="total" type="text" /></td></tr>
                    <tr><td>Tarih</td> <td><input name="date" type="text" value="'. date('d/m/y') .'" /></td></tr>
                    <tr><td>Mesaj : </td> <td><textarea name="message" cols="50" rows="5"></textarea></td></tr>
                </table>
                <center><input type="submit" value="Gönder" name="sendNotification" /></center>
            </form>';
        
        return $val;
        
    }