To copy a request, select it in the list and use the main menu item "Edit" -> "Clone Document" or the keyboard shortcut [Shift] + [Ctrl] + [C]. In the created document, the Number field will be blank. This field can be filled in manually using the keyboard, or it will be filled in automatically after saving the document.
If the original request is a child document, the cloned request will also be a child of the same parent document.