First, find and edit the article the holds the element you're looking to duplicate. In this case, we'll copy a text element from Page 1 to Page 2.
Once we find the element we want to copy, click on the Duplicate option (green "+" symbol)
Go to the page, then the article location of where you're looking to place the duplicated content element. In this case, we want to select Page 2 and duplicate the content there, but you can also place the duplicated element on the same page.
Choose the orange arrow located in the article to place the duplicated item.
This will open the element in edit mode so you can make any changes (if required). If not, simply Save and Close the element and you're done.