iPhone Duo accessory pre-orders begin this Friday. A comprehensive list of cases and screen protectors from top brands like OtterBox, Speck, and ZAGG is now available. While most retailers do not currently offer discounts, ZAGG has a promotion for 20 percent off when purchasing any two items. This deal is ideal for acquiring both a case and screen protector at a reduced price. Many of these accessories are shipping now, though some devices are slated for November or later releases. Retailers such as Amazon, AT&T, Best Buy, and Target are stocking a variety of iPhone Duo cases. Specialty stores like Burton Goods and Nomad offer leather options. OtterBox and Speck have their signature protective cases available. ESR is offering a silicone leather case with a built-in stand. For those seeking further savings, a general Apple Deals roundup is also recommended.