Bi- (as in bilingual, bilateral, etc.) cannot be derived from PIE *dwos nor Lat. duos (although some have tried hard, it remains unconvincing). It should be Vasconic as in Basque bi (two).
Paleo-Sardinian language appears to be Vasconic,according to E. Blasco Ferrer and J. M. Elexpuru.
- River names: (h)aran, ardi, baso, berri, bide, ertz, goni (goi), gorri, iri, istil, iz, lats, lur, mando, on, orri, (h)osto, (h)otz, (h)obi, (i)turri, ur, zuri.
- Village names: Aritzo, Ardaule, Asuni, Goni, Loiri, Luras, Olzai, Orgósolo, Ortueri, Osini, Turri, Ulassai, Uras, Uri, Urzulei...