Amazon typically combines shipments when you purchase multiple items from the same seller. This allows them to save on shipping costs and improve efficiency. If you have purchased items from multiple sellers, your items may be shipped separately.
When orders for items that you have already purchased are placed, they will be packed together with your other order if the following criteria is met:
Your orders were placed through one account.
Products you order are stored in the same Amazon Fulfillment Center.
All of your purchases will be shipped to the same place.
All orders will be delivered by the date promised by Amazon(The items are projected to ship around the same time).