Serveal entries in WorldConnect give the father of David Hagaman to be John Hagaman:
Father: John HAGAMAN b: 8 Dec 1780 in Southampton, Bucks Co., PA c: 25 Feb 1781 in Baptised by Rev. Matthew Leydt, Southampton Dutch Reform Church, Neshaminy, PA
Mother: Mary DE GROFF b: Bet 1780 and 1790 in probably Adams County, PA c: in Also known as Maria Degrasft, Maria Degraaft
If there is a connection, it's not readily apparent.