I've found that 'Abraham Lincoln' was a character played by Stephen Phelps, whose brothers also played the roles of his 'wife' Mary Todd Lincoln, as well as his opponents Jefferson Davis and Stephen Douglas, among a few others.

You can find him at: Stephen “Sumner” Phelps

I've put it into some context here: The End Of Deception. The Rebirth Of...

Abraham Lincoln's real name was Stephen Phelps, and his brothers played Mary Todd Lincoln, Jefferson Davis, Stephen Douglas, and others