Open PowerPoint and one of the presentations. Click the “Review” tab.
Click the “Compare” button in the Compare group. Browse and select the second presentation to combine. Click “Merge.” The presentations merge and the Revisions pane opens to the right of the merged presentations. The Revisions pane shows the differences between the two documents and allows you to accept or reject changes.
Scroll through the Presentation Changes section in the Revisions pane. This area shows slides from the second presentation to add to the first presentation. Click a slide title to display a revision checkbox. Select the revision checkbox to accept the proposed revision.
Scroll through the Slide Changes section in the Revisions pane. This area shows the differences between the two slide presentations. Click a slide change in the Slide Changes section to display a revision checkbox. Select the revision checkbox to accept the proposed revision.
Click “File” and then click “Save As” to save the presentation once you are done with changes to the two documents. Type a filename and then click “Save” to save the merged documents