The clone thing has never been referenced in other works beyond Riptide (yet). So while it is the clone in Abyss, we can't be sure if anyone knew or not.
I'm still hoping for part 3 (Undertow, perhaps?). I loved Crosscurrent, and Riptide was alright. I had a lot of trouble following it, mostly because of the clones:
a) I knew the characters like Soldier and the rest were clones of Jedi or Sith we knew from previous EU material
b) I picture characters when I read, and try and hear their voices when they speak
c) I was given NO DESCRIPTION of any of the clones until the plot twists 3/4 through the book.
As a result, I felt I couldn't connect with the characters, because I felt I should've known what they looked/sounded like, but had no idea.
Also: welcome to the forums! For future reference, we have a great thread for general Star Wars questions, over here: http://www.eucantina.net/forums/viewtopic.php?t=982&start=105
It was the year of fire… the year of destruction… the year we took back what was ours.
It was the year of rebirth… the year of great sadness… the year of pain… and the year of joy.
It was a new age. It was the end of history. It was the year everything changed.
The year is 2261.
The place: Babylon 5.