According to Mark Gurman (posting on X / Twitter), those who purchase an iPhone Duo at an Apple Store in the US will be able to have the initial setup screen customized with their name:

Fun little touch for the iPhone Duo launch: Apple retail stores will have a system to customize the boot of the device with the buyer’s name so it says “Hello, Mark” (for example) when it turns on for the first time. (US only, Duo only, English and Spanish).

I think this small detail will be a nice touch, especially given the cost of the phone. It will be interesting to see what it looks like!