Cart - only one item at a time In my cart on Commerce, I only get to have one item at a time. If I try to add another item, it replaces the item that was already in the cart.

I have used {% set cart = craft.commerce.getCart() %} and the for item in cart.lineItem to loop through the items, to no avail.
That would happen if you are using Commerce Lite. You will need Commerce Pro if you want the 'full' cart functionality.