As observed, see Identity and Provenance, visualizing who has written what is not as simple as it couldshould be. Much is Discoverable but not Obvious.
As can be seen by Understanding Page History this can be complex, containing differing Perspectives – and maybe realities. [⇒ Viewpoint]
One possible way to construct a view, of the known History of a page, is to take the Journal for the page of each of the known twins of the page. Merge them into combined history, and tease the interactions out.
A possible visualization might take this merged journal, and take inspiration from the Comic Book Narrative Charts website 
scripts.
A possible visualization
The example image is a result of coercing the journal into a form that can be used by there scripts, and was just done to explore Possibilities.
two months later...
The core of the code, reading in the pages and producing a merged journal, had been written for some time. After exploring a few blind alleys, the code now renders a view data contained in the merged journal. This is still a work in progress, but there is now something to see.
Federated Wiki Explorer
As you can see, the view is cleaner than the possible visualization that inspired this work. The journal events are laid out regularly, rather than using the event time as that provides less clear horizontal separation.
The code is written using ClojureScript, and OM for rendering.
See also - Narrative Chart - Narrative Picture