PowerPoint (and other Microsoft Office programs) let you quickly duplicate selected objects using the Ctrl+D shortcut key (for Windows). Mac users can get the same results by choosing the Command+D shortcut key. These links below provide more details on using these shortcut keys to duplicate and create a patterned sequence of objects.
To learn more, choose your version of PowerPoint. If we do not have a tutorial for your version of PowerPoint, explore the version closest to the one you use.