Remove duplicate array keys and values with case insensitive.

We have two array.
First array contains some key and values.
Second array contains some keys and values.
I want to merge this two array if duplicate values occurred remove first array duplicate value only.
I want to check key and value is case insensitive.

Please use below code for these requirements.

Code :

<?php
$alname = array(
    "CHE" => "Chennai" ,
    "JKT" => "Jakarta" ,
    "KOL" => "Kolkata" ,
    "MDU" => "Madurai" ,
    "MUM" => "Mumbai" ,
    "SHG" => "Shanghai" );

$alname1 =  array(
    "TKY" => "Tokyo" ,
    "MXI" => "Mexico City" ,
    "DHI" => "Delhi" ,
    "KAR" => "Karachi" ,
    "CHN" => "CheNnai" ,
    "ShG" => "ShaNghai" ,
    "ISB" => "Istanbul" );
   
    echo "<pre>";
    echo "<br/>First Array : <br/>";
    print_r($alname);
    echo "<br/>Second Array : <br/>";
    print_r($alname1);
   
    $arr2 = array_merge($alname,$alname1);
    echo "<br/>Merge first and second array Before remove duplicate values : <br/>";
    print_r($arr2);
   
    foreach($alname as $alkey => $alval)
        {
           $slow_key = strtolower($alkey);
           $slow_val = strtolower($alval);
           $slow_alname1 = unserialize(strtolower(serialize($alname1)));
           $slow_alname1 = array_change_key_case($slow_alname1,CASE_LOWER);
           if(isset($slow_alname1[$slow_key]))
           {
             unset($alname[$alkey]);
           }
          
           if(in_array($slow_val,$slow_alname1))
           {
              unset($alname[$alkey]);
           }
          
        }
        $arr2 = array_merge($alname,$alname1);
        echo "<br/><br/>Merge first and second array After remove duplicate values : <br/><br/>";
        print_r($arr2);
        echo "</pre>";
       
?>


OUTPUT :