How to Duplicate a PowerPoint 2007 Slide
PowerPoint sports a Duplicate Slide command that lets you duplicate an entire slide. That way, after you toil over a slide to get its formatting just right, you can create a duplicate slide to use as the basis for another slide in your presentation.
To duplicate a slide:
Select the slide(s) you want to duplicate.
In Slides view click the thumbnail of the slide you want to duplicate.
Open the Home tab.
You’ll find the Home tab on the Ribbon.
Duplicate the slide.
Click the arrow at the bottom of the Add Slide button in the Slides group, and choose the Duplicate Selected Slides button.
A duplicate of the slide is inserted into your presentation.
If you’re a keyboard shortcut fanatic, all you have to do is select the slide that you want to duplicate in the Slides pane (located on the left side of the screen) and then press Ctrl+D.