<?

$array1 = array(1=>1,10=>1,12=>0,13=>13);
$array2 = array(1=>"Hello",10=>"Test",12=>"check",13=>"error");

$prev = $array1[1];

foreach($array1 as $key => $val)
{
    if($val != $prev && $key != 1)
    {
        echo '<br />';
    }

    echo $array2[$key].' ';
    
    $prev = $val;
}

?>

Hello Test <br />check <br />error