I think I solved the mystery of "Piedimonte Oliva", where my great-grandfather's and great-great-grandmother's shipping record said they came from. Piedimonte Matese is the somewhat larger town next to San Potito Sannitico, where my great-grandfather is from. On the Italian Genealogy Home Page's bulletin board, there's a page for messages with the subject "Piedimonte d'Matese formerly D'Alife". Did the town change its name? I went searching in the LDS catalog for the town of Piedimonte Matese, and came up with a page that says (Use for) Italy, Caserta, Piedimonte d'Alife. Drilling down a little further brings a page that says that Piedimonte Matese was known as Piedimonte d'Alife until 1970.
d'Alife would be pronounced roughtly "d-uh-LEEF-uh"; "oliva" would be pronounced "uh-LEEV-uh". Someone who wasn't familiar with the name of the town, for example, the ship's master, might mishear d'Alife as Oliva. Hence the reference to Piedimonte Oliva for people from Piedimonte d'Alife. QED. Well, kinda. It makes sense to me, anyway.
Oh, and interestingly enough, one of the postings on the Italian Genealogy Home page bulletin board, the one linked to above, says that people looking for more information about Piedimonte Matese should e-mail one Vincenzo Rapa. The plot thickens....
Posted at 7:06:41 PM