check equal value in php

This code I want to use it for barcode scanner. Insert in input "insert_code" the cod scanned with barcode scanner. I need this code to return "code is ok", when search_code = insert_code. My code, after validation, delete input search_code and difficulty for me to introduce in search_code same code every time. What can I do not delete search_code to each validation?

<form action="" method="post">
    Cod I:<input type="text" name="search_code" value=""/><br/><br/>
    Cod II:<input type="" name="insert_code" value=""/><br/><br/>
    <input type="submit" name="button" value="validation" />
</form>

<?php

$search_code = $_POST ["search_code"];
$insert_code = $_POST ["insert_code"];

if ($search_code == $insert_code){
    echo "code is ok";
}
  else {
      echo "code is not ok";
  }
?>