1)
Here it says that he took from Betach and Berosi. In Divrei ha'Yamim I, 18:8, it says from Tivchas and Kon!
1.
Radak: Each city had two names. Betach and Tivchas are the same, just the letters are reversed.
2.
Malbim: Their names changed. There it explains that Shlomo used the copper to make the Yam (a Mikveh), pillars and copper Kelim.
