Have you learned anything more on the Sarah "Sallie" Patrick issue?
My "best guess" is, that Matthew Arney, Sr. married Sarah "Sallie" Pharris (Farris) first, and that she died young, then he married Sarah "Sallie" Patrick later.
I cannot confirm either of these marriages, due to the loss of early marriage records, with the burning of the Overton County Courthouse, at the end of the Civil War, in 1865.
Also, I have been unable to find Matthew Arney, Sr. in any 1850 US Federal Census.