Pramāṇadvitvasiddhi by Arcaṭa
Not preserved. See Hetubinduṭīkā Sanghavi, Muni Śrī Jambuvijayaji 1949; A. K. Warder (Indian Buddhism, Delhi, Motilal Banarsidass, 2nd revised ed. 1980, p. 472) says: "the Pramāṇadvitvasiddhi [a lost work of Arcaṭa] . . . appears to be the same as the Pramāṇāntarbhāva (Notes/appendix to Manorathanandin's Pramāṇavārttikavṛtti) . . .", but does not justify this assumption.