Fight Club!
I don't know if it really is the case, but The Testament of Dr Mabuse uses themes very similar to Chuck Palahniuk's "Fight Club" - double identity mastermind organizing terrorist attacks against the society, to be precise. Now while in Lang's film the organized crime thing is a kind of manifestation of pure evil (the Empire of Crime, total anarchy etc) and thus differs from the motives given in Palahniuk's/Fincher's "Fight Club", the two stories share a number of similarities - the love story of Tom Kent, for example, could be the basis of Jack's/Dyrden's affair between Marla etc.
I know it's a long shot, but postmodern writers - when they rewrite original narratives - tend to hide and mix different elements they base their works upon. Could this be the case? Or is my imagination running wild here?