The option to duplicate a task is accessible from the task, either in minimized mode:
... or in full screen mode:
After selecting the Duplicate task option, the modal screen that displays allows you to specify the task information to be duplicated.
First, enter a name for the duplicated task. Then select the location where you want to duplicate the task, i.e. the project, the task list and the status.
To complete the location, you must specify whether you want to duplicate the task before the existing tasks in the status or at the end of the status.
Once the location of the duplicated task has been defined, you will need to determine which elements of the task you want to duplicate.
Once you have made your selection, click the Duplicate button.