How can I duplicate a FootageItem object via scripting?

Hi There,

I am trying to understand why I cannot duplicate a FootageItem object in the same manner as a CompItem object.  For example, if I am iterating through a composition and encounter a layer that is of type CompItem, I can do this:

dupe = layer.source.duplicate()

. . . and with that, I will get a duplicate of the layer's source (a composition) in the project panel. 

However, if I encounter a layer that is of type FootageItem, then I cannot use the .duplicate() method.  Using the same code above, ESTK gives me this error on a layer with a source type of FootageItem

Error: Function l.source.duplicate is undefined

What is the necessary code to duplicate a FootageItem?

I want to understand how I can duplicate a footage item that is used for a layer.  I do not want to duplicate the layer itself, but its source.

Thanks for your time and help!

--Arie