Slides can be duplicated using the option 'Edit -> Duplicate' from the menu bar. Using this,
similar slides are created by selecting a slide from the Slide Pane. Duplicate Slides in Microsoft Powerpoint 2002
In the example, the same slide is duplicated thrice using the duplicate option.
This option will be enabled only if a slide is selected in the 'Slide Pane'.
Outline pane is checked to see all the 3 duplicate slides.