Using libmcrypt-2.2.4, PHP 4 (Latest CVS) as Apache 1.3.9 module.
Extra chars are being added either at the encryption or decryption stage using mcrypt_ecb().
This script is an adaption of the script in the PHP manual.

<?php
$key = "this_is_my_key";
$input = "123456789";
printf ("Input Text: %s Count:%s\n", $input, strlen($input));
$encrypted_data = mcrypt_ecb(MCRYPT_TripleDES, $key, $input, MCRYPT_ENCRYPT);
$decrypted_data = mcrypt_ecb(MCRYPT_TripleDES, $key, $encrypted_data, MCRYPT_DECRYPT);
printf ("Decrypt Text: %s Count:%s", $decrypted_data, strlen($decrypted_data));
?>

Output:
Input Text: 123456789 Count:9
Decrypt Text: 123456789        Count:16