You can duplicate existing pages in your project from the Pages screen:
Duplicate a single page
Select the three dots in the top right corner of the page you would like to duplicate, and select Duplicate from the menu shown:
Duplicate multiple pages
To duplicate one or more pages, select the pages you would like to duplicate by clicking the circle in the top left corner of each page and then selecting Duplicate in the top right corner of the Pages view:
Each duplicated page will be inserted next to the original one.
You can duplicate an entire chapter by clicking the three dots in the top right corner of the chapter and select Duplicate Chapter from the menu shown:
The duplicated chapter will be placed after the original one.