Greenbrier County death records lists Amanda Perkins (varient spelling isn't significant) died Scarlet Fever May 1855 age 2 months, Father Beneah, mother Mary.
Margaret F. Perkins died 11 April 1854 age 1 month 23 days. Father Beniah, mother Amanda.
So there is Beniah with two wives. Possibly the mother was Mary Amanda. I have no other information on Beniah and don't know which Parkins line her belonged to. I've been puzzled by him as well; sorry I can't help.