PHP_Toolkit 20.0 Create Duplicate

Question

I am using this example in order to create a new Contact on SF, my question is what happens if the Contact I am creating exists on Salesforce, how can I create that check or how can I tell Salesforce to only look at the email when I am trying to insert a new Contact because I don't want to have 2 Contacts with the same Email. (Using Email as sort of an ID for every user).

Code used in the example:

<?php
// SOAP_CLIENT_BASEDIR - folder that contains the PHP Toolkit and your WSDL
// $USERNAME - variable that contains your Salesforce.com username (must be in the form of an email)
// $PASSWORD - variable that contains your Salesforce.ocm password

define("SOAP_CLIENT_BASEDIR", "../../soapclient");
require_once (SOAP_CLIENT_BASEDIR.'/SforceEnterpriseClient.php');
require_once (SOAP_CLIENT_BASEDIR.'/SforceHeaderOptions.php');
require_once ('../userAuth.php');
try {
  $mySforceConnection = new SforceEnterpriseClient();
  $mySoapClient = $mySforceConnection->createConnection(SOAP_CLIENT_BASEDIR.'/enterprise.wsdl.xml');
  $mylogin = $mySforceConnection->login($USERNAME, $PASSWORD);

  $sObject = new stdclass();
  $sObject->FirstName = 'Smith';
  $sObject->LastName = 'John';
  $sObject->Phone = '510-555-5555';
  $sObject->Email = '[email protected]';


  $sObject2 = new stdclass();
  $sObject2->FirstName = 'Smith';
  $sObject2->LastName = 'John';
  $sObject2->Phone = '510-555-5555';
  $sObject2->Email = '[email protected]';

  echo "**** Creating the following:\r\n";
  $createResponse = $mySforceConnection->create(array($sObject, $sObject2), 'Contact');

} catch (Exception $e) {
  echo $mySforceConnection->getLastRequest();
  echo $e->faultstring;
}
?>

Basically, I want this query to work and SF to create two different contacts, use ONLY the email as a check for duplicates. Right now I am getting this error:
Standard_Contact_Match_Rule_v1_1
Contact_with_same_email_already_exists_in_SF

EDIT: I have tried to play with the library source and still can't get AllowSave to work. Here are the code changes:
SforceBaseClient.php Line 51:

class SforceBaseClient {
    protected $duplicateRuleHeader; //Added

SforceBaseClient.php Line 226:

if ($call == "create" ||
    $call == "resetPassword" ||
    $call == "update" ||
    $call == "upsert"
    ) {
        $header = $this->duplicateRuleHeader;
        if ($header != NULL) {
            array_push($header_array, $header);
        }
    }

SforceBaseClient.php Line 347:

public function setDuplicateRuleHeader($header) {
    if($header != NULL) {
        $this->duplicateRuleHeader = new SoapHeader($this->namespace, 'DuplicateRuleHeader', array (
                'allowSave' => $header->allowSave,
                'includeRecordDetails' => $header->includeRecordDetails,
                'runAsCurrentUser' => $header->runAsCurrentUser
            ));
    }
    else {
        $this->duplicateRuleHeader = NULL;
    }
}

SforceHeaderOption.php Line 74:

/**
 * To be used with Create and Update operations.
 * Only one attribute can be set at a time.
 *
 * @package SalesforceSoapClient
 */
class DuplicateRuleHeader {
    // boolean
    public $allowSave, $includeRecordDetails, $runAsCurrentUser;

    /**
     * Constructor.  Only one param can be set.
     *
     * @param boolean $allowSave  allowSave flag
     * @param boolean $includeRecordDetails  includeRecordDetails flag
     * @param boolean $runAsCurrentUser  runAsCurrentUser flag
     */
    public function __construct($allowSave = NULL, $includeRecordDetails = NULL, $runAsCurrentUser = NULL) {
            if($allowSave != NULL) {
                $this->allowSave = $allowSave;
            }
            if($includeRecordDetails != NULL) {
                $this->includeRecordDetails = $includeRecordDetails;
            }
            if($runAsCurrentUser != NULL) {
                $this->runAsCurrentUser = $runAsCurrentUser;
            }
    }
}

I'm calling:

$header = new DuplicateRuleHeader(true);
$mySforceConnection->set setDuplicateRuleHeader($header);

I still get the Duplicate contact error, any ideas? what am I missing?