Where it usually starts
A pet shop that sells online through a generic template lists the same dog food six times, once per bag size, so stock is counted in six places and the fifteen-kilogram bag shows as in stock when only the two-kilogram is on the shelf.
- A customer whose dog eats one large bag a month orders it on the first of the month until the month they forget, and the shop loses the sale to a subscription supplier.
- The till in the shop and the website keep separate stock, so a Saturday sale in the shop leaves the website selling a bag that is already gone.