If you have multiple presentations open simultaneously, you can cut or copy a Lesson from one presentation and paste it into the other presentations.
Note: Lessons with mobile slides (.mprs) cannot be pasted into presentation files (.prs), and vice versa.
To copy/cut and paste a Lesson across multiple presentations
This will copy and remove the selected Lesson from the Presentation Layout pane.
The Lesson is added as the first Lesson. If a Lesson was selected when the copied/cut Lesson was pasted, the new Lesson is added below the selected Lesson.