Currently there is no setting to automatically duplicate pages within your site. New pages must be manually added and configured, and then the content can be duplicated in the new page. You can type the content within the page editor, or you can copy the HTML from the existing page and then paste that within your new page.
To view and copy the HTML for a given page, open the editor for the current page and click the html link in the editor toolbar. Copy the HTML code for your page and use the same process to insert that copied code into your new page. Save and close the editor to see a duplicate of your original content.
Note: System-structured pages like Galleries, Form pages, FAQ, etc. cannot be duplicated by copying HTML code. For these, you'll simply need to manually recreate the page from scratch.