If you have recently ordered from a store and the order hasn't been marked as paid, packed or shipped yet, the system will add to that order instead of letting you place a new one. When an order is submitted, all items in that order are flagged as batch #1. If that order is added to, all items in that addition will be flagged as batch #2. If the order is added to again, all items will be flagged as batch #3 and so forth.
If the store has a minimum order amount, you do not need to reach that amount again to add to your original order. Simply add the items to your cart and when you checkout, the order will be added as a new batch to the original order.
The order status will change to Updated, payment status to None, the order date, order status change date and order payment status change date will be set to the current date.