show if area not correct show

I created a web form for login/register user in the same form. All work but
using show if area if the login fails the area show a message (and this is correct)
but if the login success the area always show the same message and I don't want this.

Also when unique validation fails the correct redirect address is blog_details.php?idarticolo=1
but I have:
blog_details.php?idarticolo=1&idarticolo=1.
eed help

this is server validation in blog_login_fails.php
<?php
if ("" == "") {
$WAFV_Redirect = "blog_details.php?idarticolo=".$_SESSION['nonregistrato']['idarticolo']."";
$_SESSION['WAVT_blogloginfails_485_Errors'] = "";
if ($WAFV_Redirect == "") {
$WAFV_Redirect = $_SERVER["PHP_SELF"];
}
$WAFV_Errors = "";
$WAFV_Errors .= WAValidateUnique("siicom",$siicom,$database_siicom,"user","iduser","none,none,NULL","0","mail","',none,''","".($_SESSION['nonregistrato']['mail']) ."",true,1);

if ($WAFV_Errors != "") {
PostResult($WAFV_Redirect,$WAFV_Errors,"blogloginfails_485");
}
}
?>

and this is show if in blog_details.php from line 282

<?php
if (ValidatedField('blogloginfails_485','blogloginfails_485')) {
if ((strpos((",".ValidatedField("blogloginfails_485","blogloginfails_485").","), "," . "1" . ",") !== false || "1" == "")) {
if (!(false)) {
?>
<p class="error">L'email o la password che hai inserito sono errate. Prova di nuovo oppure Recupera i dati</p>
<?php //WAFV_Conditional blog_login_fails.php blogloginfails_485(1:)
}
}
}?>

On the blog_details.php page, add the following code after the </html> tag:

<?php

if(isset($_SESSION['WAVT_blogloginfails_485_Errors'])) unset($_SESSION['WAVT_blogloginfails_485_Errors']);

if(isset($_GET['idarticolo'])) unset($_GET['idarticolo']);

?>

Now work fine. Thank