You can edit multiple slides at once using the Bulk Actions feature. By selecting multiple slides in the Edit view, you are able to copy, delete, move or skip several slides with one simple action.

If you want to select multiple slides at once, hold the Shift or Ctrl key (Command for Mac computers) and click on the slides you want to edit.

Once selected, you can right click any of the slides to reveal the bulk action menu:
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Now you can duplicate, copy, skip or delete the slide you've selected. You can also drag and drop the selected slides to reorder the presentation.