Are you sure they weren't the same person? Oregon and Ripley are adjoining counties.
The Nat'l Archives site lists Porter Moore but no P. L.:
http://www.nps.gov/civilwar/search-soldiers-detail.htm?soldi...When you click on link for the 12th it states it was "also called 3rd" and lists action in Arkansas and Louisiana.
The Mo. Archives site lists only P. L. and also lists action in Arkansas and Louisiana:
http://www.sos.mo.gov/Images/Archives/Military/s00736/s00736...Both were Confederate units and if not the same, he may have served in both.
I don't find either a P. L. or Porter Moore in 1860 census southern Mo.