The Robert Abernathy referenced in Deed 1 was very probably Robert (3rd) and his wife Mary. After many years of investigation by numerous expert researchers (Harwell and Abernathys alike), there has still not been one single shred of evidence turned up to substantiate the supposition that her maiden name was Harwell.
The Robert Abernathy referenced in Deed 2 was quite likely Robert (5th) and his wife Ann Nance/Nantz. If it was Robert (4th) then it would be the _only_ instance where his wife was refered to as anything other than Sarah. And this is one reason why I distrust abstracts. In all too many cases when I have finally gotten around to looking at the actual image of the item that was abstracted, certain information and sometimes very critical clues was omitted in the abstract.
Finally, do remember that in the time frame when these documents were initially created, the designations "Jr" and "Sr" designators were not used as they are today and the older of such a so-called pair might not be the Father of the younger. Cousin or Uncle perhaps. But not necessarily the Father, merely the elder of two men in the same area who happened to have exactly the same name designation.
The James Abernathy referenced in the 2nd deed was very likely a grandson or gr-grandson of the 1st Robert and probably moved on to the Lincoln County NC area along with the Rocketts and other Abernathys around 1768. To my current knowledge, the first instances in the Lincoln County area of members of the Abernathy family from Virginia was a land purchases on 20 Aug 1769 and a sale of land on 21 Feb 1770 (both by the 4th Robert).
Finally, I do not believe that the 3rd Robert ever had an original grant in NC, whether in Granville County or elsewhere. Inherited land in VA, yes. Purchased land in Carolina from someone who may have had an earlier Colonial grant, perhaps. But otherwise, I find no evidence for an original grant to the 3rd Robert in that area along the border between Virginia and North Carolina.