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
Description:
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.