Remember Diane said they she knows a Janney E but they have been estranged for a long time.  

Maybe Mike created Dougie to enable Coop to come back in the future. 

Maybe when Mr C "took over" Diane she actually became Janney E. 

This would explain the care that Janney E took of Dougie.

Would you not take a virtual stroke victim that is your husband to a doctor? 

Maybe not if you knew something...

What about the look she gives the new Coop while driving in the car. A look of  "you are back".

Janney E or Dougie got the Dougie Janney E ring into Briggs gut to lead the FBI to Las Vegas we know that... but how and when.

Or I could be totally wrong. Dealers choice.  🙂