I think it's much more likely that 1138 is another crazy clone who busted out somehow.
If he wasn't a product of the project cooked up to create a stable clone of Galen, then why would the original apprentice be given a designation like the clones being grown? If anything, wouldn't he be called Subject 1 or something?
"There is something going on in time and space, and beyond time and space, which, whether we like it or not, spells duty." -Winston Churchill
"For of all sad words of tongue or pen, The saddest are these: 'It might have been!'" -John Whittier
"Apathy is death." -Kreia