While you cannot copy a chapter to another manual, you can copy the articles from one chapter to another using the "Add Article" dialog. If you want to make a copy of content in a chapter and add it to a chapter in another manual then follow these steps.
1. Create a new chapter
1.1. Include a Title > Save Chapter
2. Select Add existing article from the chapter action menu
3. Duplicate articles
Navigate to the chapter that has the articles you would like to add. While you can Reference or Move articles when adding them to a chapter, for our purposes here we can to Duplicate the articles. Click the Duplicate button next to each article that you want to add.
When you are done duplicating articles click the Done button.
Publishing the articles in the chapter
After you add the articles, they will not be published. If you want to publish them all at once, simply click the chapter action menu and select Publish.