Okay... but that leaves with another question for me, though
Where did FWR kidnap himself another Syaoran if it isn't the Syaoran from CCS world?
So is FWR related to Clow of Tsubasa world or Clow of CCS world?
I think you're missing the point (or ideal) of the Tsubasa: RC universe. ^_^ Throughout Tsubasa: RC, we find out that there are many dimensions out there. In each dimension, there can be "another you" living there. That "other you" may have a similar or complete opposite nature of your own. You can be good here on Earth, but on some other world, that "other you" can be evil.  Therefore, you and the "other you" may be different but your souls are still the same no matter what. (Can be a bit confusing but it's pretty easy to grasp.)
Therefore, there can be millions of Syaorans across the dimensions!  O_o (Scary thought, actually.)  Their personalities or nature may be different, but their souls are the same.  Think about it.  There should be more Syaorans than just the Real!Syaoran and CCS Syaoran, right? Clone!Syaoran can count sort of, but it's really the heart of Real!Syaoran that's making the clone real. Â
   Same concept with Clow Kingdom and CCS world. They are two different dimensions, yet, a lot of the same people exist in both of those dimensions.
Now, to answer your questions.  The truth is, we don't know.  How FWR and Real!Syaoran met, where they met, how they knew each other, etc.  The past of Real!Syaoran isn't clear yet. We are only touching the surface of the past in Chapitre 119. Real!Syaoran could be from Clow Kingdom's dimension but he could pretty much be from any dimension that contains Clow Reed (with the exception of CCS world because that world's story is over now). ^_0
I think I remember reading that FWR has lineage to Clow Reed (which means he could be a direct descendant). That would make both him and Real!Syaoran have something in common, but for now. We don't know the full truth either.  There can be many Clow Reeds across the dimensions too, just like everyone else. Heh...
 Sorry for the semi-long explanation! >_<  ^o^  I hope you understand a little better though. Wait patiently for CLAMP to answer everything we've been longing to know for such a long time.  Â