To copy a page from your existing ones, simply go to Pages -> go on top of the page you want to duplicate and click on the 3 dots, then select Duplicate
To create a page from your existing template pages go to Pages -> Add New -> Page and select Existing Page button
Then in the Page Creation popup from the Page Template select the page you want to duplicate. You have two options:
Template page - select one of the page designs from the original template you selected
My pages - select a page from your curent website that will be duplicated exactly
