Select the section you want to duplicate and click on the settings icon on the top right of it.
Click on Copy Component.
The duplicate section should appear below the section you copied.
Alternatively, you can click on Save as Reusable Section to make a copy of the selected section.
Click on the New Section button.
Select Saved Section.
On Saved Blocks, you can see the section you saved earlier. Select the section you want to copy.