Seem like this feature was removed from xcode 5 ?
Prior to xcode5, it is easy to duplicate any target via clicking on the target, choose "duplicated blabla", then you will get it.
But for xcode5 , where is this hiding ?
Step1: Select the (blue) project icon in Xcode and open project setting page.
Step2: Click on the black arrow icon and explore the targets
Step 3: Duplicate your target by selecting the target and press "cmd+D" keys. You can rename as you like.
Enjoy!!
Select your project in the left nav. In the main content area at the top, you have a row that is like a file navigator. Then the second row, right under the first, in the very left there is a little square arrow thing. That hides/shows the project and targets list.
It's still there - right click on target or use CMD + D
shortcut after selecting target