Are you referring to The original katherine as in TATIA the proginor of the petrova family line? Not to say that it isn't possible but Tatia was born in the 10th century. Silas existed in the 1st century.... That means that there would be another one before tatia which wouldn't make sense. However we know silas mystery lover was a brunnett we can assume being that he said he has a intrest in brunnetts.
Well, doppelgangers are born every 500 years so in a way it could be possible. Only then there would have been one more doppelganger in between this one and Katherine. I've been thinking about it too. Maybe her death (Silas' lover) caused the doppelgangers to spawn and because of the powerfull blood doppelgangers have Esther used it later in her spell to make her children immortal. Maybe Esther knew that Tatia was more than just a beautiful girl. And when performing the spell she bound the doppelgangers life and Klaus' curse together. Before that, the doppelgangers were just doppelgangers and died after a normal human's lifetime. But where did she get her spell from? How did she got it? Since they're supposed to be the first vampires it could be that somehow she got a hold on Silas' spell. There were no vampires before that. He and Qetsiyah were the only other ones who also used an immortal spell. But again, how the heck did she got her hands on it? There's still so many holes in this theory, but I have to say I do really like it !!