As seen in Incredible Hulk #5 (2012) we now that Banner and Hulk were seperated by Dr.Doom. During the seperation process Hulk placed Banner deep within his mind where he wouldn't know what was going on. During the procedure Doom essentially cut "Banner" from the Hulk's brain and placed him inside a newly cloned body. However, judging by the personality shift and the overall malicious attitude, I would argue that "Banner" is still locked inside the mind of the Hulk while the entity inside of the clone Banner body is the Devil Hulk. Whether or not Doom placed him in the body intentionally will remain to be seen. Should clone Banner ever attain a gamma transformation his true identity will be revealed.