Want to use the same placeholder several times throughout your project? This tutorial shows you how!
Another way to achieve this is by re-importing the same project into the one that you currently have open thereby creating a new set of placeholders inside the imported project.
You can repeat this process as many times as you wish, or you can Save as different projects and export them as QuickTime files that you can then piece together back in Premiere Pro.
For a more detailed look at how to import projects, check out this video tutorial: