The Grand Duel

1972 spaghetti western. From iMDB:
Philipp Wermeer has been framed for the murder of a powerful figure known as The Patriarch. Wermeer escapes, but the three Saxon brothers, sons of The Patriarch, have arranged for a large bounty on Wermeer's head. Clayton is a grizzled ex-sheriff stripped of his office in Jefferson after refusing to acknowledge Wermeer's guilt. During a series of fire-fights, Clayton contrives to help Wermeer escape from attacks of bounty-hunters. Together, the two make their way to Jefferson, where they can confront the three powerful Saxon brothers, and reveal the surprising truth about who killed The Patriarch.