BasketBase::copy

public function copy()
{
	if($this->order !== null)
	{
		throw new MainSystemException('Could not clone basket which has order.');
	}

	$basket = static::create($this->siteId);
	/**@var BasketItemBase $item */
	foreach($this as $originalItem)
	{
		$item = $basket->createItem($originalItem->getField("MODULE"), $originalItem->getProductId());
		$item->initFields($originalItem->getFields()->getValues());
	}

	return $basket;
}