Hi Juliet,
This really depends on how you wish to treat them. If they are separate customers (you bill them separately as each buys different products or services) then I'd enter them as separate leads. Then when they become customers, you can add them as a job of customer, with each store being a job of a main customer.
If you really only have contacts from different stores, then I'd suggest putting each store contact as a contact in Method. This way, each store has a contact, but there is only one Lead/Customer that is billed, buys products, etc.
Hope this helps.
Adam