A Gunfight (1971) on Netflix

Two aging gunfighters in need of money come to an agreement to organize an actual showdown between them and sell tickets for it. The townsfolk is more than interested to see the "show".

Will Tenneray and Abe Cross are two famous gunfighters who are getting old and need money. Cross tried his luck at gold prospecting but failed. Tenneray works at the local saloon where he capitalizes on his past fame to "sucker fools into buying drinks". The town expects them to become enemies and kill each other in a gunfight but the two aging gunfighters start liking one another. Desperate for money, Tenneray suggests to Cross to put on a show for the townsfolk and fight in an arena for money. The proceeds from the ticket sales would go to the winner of the gunfight. Both men like the idea of a paid show but hate the possibility of one of them killing the other.

—nufs68