In a statement shared with MacRumors today, an Apple spokesperson said there will be "limited" availability of the iPhone Duo for walk-in customers at Apple Stores in select countries when the device launches this Friday, October 23. Apple’s full statement: On Friday morning, our teams look forward to welcoming customers at Apple Stores to experience iPhone Duo and the incredible iPhone line-up for themselves. Apple Stores will have limited iPhone Duo available for walk-in customers, and we’re working hard to get this revolutionary new product into customers’ hands as quickly as possible. Apple said that given the "extraordinary" pre-order demand for the iPhone Duo , it expects that supply will sell out quickly on Friday…