do functions overwrite when its included multiple times?

[kohan]

I have created a couple functions

a.php

<?php 
  function a ()
  {
      echo "this is a <br>";
     ?>
    <tr><td>this is from html</td></tr>
    <?php
  }
?>

ab.php

<?php
include "a.php";
a();
?>

b.php

<?php
include "ab.php";
include "a.php";

echo "b <br>";
a();
?>

I figure it'll probably overwrites when the code is included again in b.php.
Can anybody verify this and let me know what's going on in the file?
Thanks

[cahva]

No, funtions do not get overrided. PHP will spit an error that function is allready declared.