Why does it say that there are 14 cities? There are 15!
Rashi: Tapu'ach veha'Einam (verse 34) are one; veha'Einam is the spring Ein Tapu'ach mentioned in Menasheh's portion. 1
Radak: Perhaps ha'Gederah and Gederosayim are one place. Metzudas David
Rashi (16:1) says that Bnei Yosef received at the north of Yehoshua's conquest. Yehudah was in the south; Binyamin and other Shevatim were in between. How can a spring be in Menasheh's portion, and also in Yehudah's (and here it lists interior cities of Yehudah, and not on its border! - PF)
(He also authored Kli Chemdah on Chumash. R. Shlomo Luntshitz authored Kli Yakar on Chumash.) Pesikta Zutresa (Bereishis 38:14) says that Pesach Einayim is the name of a place, like Tapu'ach veha'Einam. However, perhaps it means like Sotah 10a and other Midrashim, that ha'Einam by itself is the name of a place. (PF)