If you want to duplicate a column of tasks or an individual task, you can do so from the Task Board.
From the Task Board, click on the Column menu to copy the entire column and all its tasks. You can copy a Column to the current module or to any number of different modules from the same place.
The Column will be added to the destination module on the left, so you can easily drag it into final position.
Likewise, click on an individual Task to copy that task.
You can duplicate the task in the current module, or in any number of different modules. Choose the target module(s), and then choose the column placement of the Task. You can also choose to notify the learners in the destination module about the placement of the new task.
Whenever you copy from one module into others, a confirmation will appear with links to the destination modules so you can remodel and revise the copies you made.
To see how these features play together in a real scenario, enriching an active module with existing parts from other modules, take a look at this feature overview video (2m40s.)