Yar and the Ent-C

[Killallewoks]

Ok so its going to get complicated but ah well you'll live any way, after the destruction the of the USS Enterprise C and the subsequent capture of the survivors does this mean that there were two Yars in the same universe? And that the events leading up too the Ent-c going foreward in time was also an invetability thus creating a paradox? Or did this create a completly new timeline? 

[Morgan]

does this mean that there were two Yars in the same universe?

Yes.  One was native to the "normal" timeline, the other one wasn't.

And that the events leading up too the Ent-c going foreward in time was also an invetability thus creating a paradox? Or did this create a completly new timeline? 

I'd say it's open to interpretation.  I look at it as the Enterprise-C having an encounter with an alternate reality long before the Enterprise-D was even on the drawing board, and that encounter had consequences for "our" universe.

[mckinneyc]

The fallout was clear, Sela was born and she started trying to cause the Federation/Klingon Alliance to fall apart and to conquer Vulcan.

Other than that I don't think it changed the timeline too much as these incidents were confined to the Klingon Empire and the reunification plan was prevented thanks to Spock and the Enterprise-D crew.