Função limit_words causa erro fatal

Fatal error: Cannot redeclare limit_words() (previously declared in C:\wamp\www\Marketing\wp-content\themes\marketing\functions.php:16) in C:\wamp\www\Marketing\wp-content\themes\marketing\functions.php on line 10

P/Q esta dando esa notificação e a função não funciona ?

header.php
<?php include (TEMPLATEPATH . '/functions.php'); ?>

functions.php

<?php
function limit_words($text, $limit = 25)
{
	$words = split(" ",$text);
	$str = "";
	for ($i = 0; ($i < count($words) && $i < $limit ); $i++)
	{
		$str .= $words[$i] . " ";
	}
	return $str;
}

?>

index.php

<?php
echo limit_words(get_the_content(), 10);
?>