version 2.1.1 (current)
Line 544:
			if($userInDB->user_cms_id){
Line 548:			
			$this->user_id = $userInDB->user_id;

Taken from this section within file:
if($simplified==2){
	$this->database->setQuery('SELECT * FROM '.hikashop_table('user').' WHERE user_email = '.$this->database->Quote($userData->user_email));
	$userInDB = $this->database->loadObjectList();
	if($userInDB->user_cms_id){
		JError::raiseWarning('', JText::_('EMAIL_ADDRESS_ALREADY_USED'));
		return false;
	}
	$this->user_id = $userInDB->user_id;
	if(!$this->user_id){
		$this->user_id = $this->save($userData);
	}
	$query = 'UPDATE '.hikashop_table('address').' AS a SET a.address_published=0 WHERE a.address_user_id='.(int)$this->user_id.' and a.address_published=1';
	$this->database->setQuery($query);
	$this->database->query();
}else{
	$this->user_id = $this->save($userData);
}
if(isset($addressData->address_id)){
	unset($addressData->address_id);
}
$this->registerData->user_id = $this->user_id;
if(!empty($addressData)){
	$addressData->address_user_id = $this->user_id;
	$addressClass = hikashop_get('class.address');
	$this->address_id = $addressClass->save($addressData);
}

-------------------------------------------------------------------------

version 2.0.0 (previous)
Line 544:
			$this->database->query();
Line 548:
			if(isset($addressData->address_id)){

Taken from this section within file:
if($simplified==2){
	$this->database->setQuery('SELECT user_id FROM '.hikashop_table('user').' WHERE user_email = '.$this->database->Quote($userData->user_email));
	$this->user_id = $this->database->loadResult();
	if(!$this->user_id){
		$this->user_id = $this->save($userData);
	}
	$query = 'UPDATE '.hikashop_table('address').' AS a SET a.address_published=0 WHERE a.address_user_id='.(int)$this->user_id.' and a.address_published=1';
	$this->database->setQuery($query);
	$this->database->query();
}else{
	$this->user_id = $this->save($userData);
}
if(isset($addressData->address_id)){
	unset($addressData->address_id);
}
$this->registerData->user_id = $this->user_id;
if(!empty($addressData)){
	$addressData->address_user_id = $this->user_id;
	$addressClass = hikashop_get('class.address');
	$this->address_id = $addressClass->save($addressData);
}