Additional demand
Additional demand is the need for customers who already own a particular product to additionally purchase a second or subsequent one. Think of a second car or a second television. Additional demand always involves additional copies of durable consumer goods, purchased before the first one is due for replacement.
The presence of (and response to) additional demand can generate sales from customers who have already made an initial purchase and where there is not yet replacement demand.
With consumables such as groceries, buying additional copies of an item is not an additional purchase but a repeat purchase.
