One customer can have product X in cart. If one customer have that product , other cant add to cart. There is 1 hour time for customer to order that product. If not ,after 1 hour it will be deleted from cart. Now other customer can add to cart. And keep 1 hour. It is good if you have product with qty 1 , second hand clothes, art pictures, only one of kind products, etc . And you don't want 2 customer to buy same product.
https://www.opencart.com/index.php?rout ... n_id=29031