An autograph book signed by both "Wild Bill" Hickok and "Buffalo Bill" Cody is expected to make more than $15,000 at Heritage Auctions.
The Legends of the West sale takes place in Dallas on June 11.
Both wild west folk figures signed the book while performing in Scouts of the Plains (a play written by Cody) on the east coast in 1873-1874.
Cody has inscribed the paper: "W.F. Cody 'Buffalo Bill'/ Once a scout and guide but now a thin actor/ Norwich, Connecticut/Jan. 15/74".
Hickok has signed twice - enhancing its desirability, as his signature is very rare.
An autograph from "Texas Jack" Omohundro, another well-known cowboy and the co-writer of the play, is also included.
The play itself is reported to have been terrible.
Offstage the cast indulged in brawls, drinking and all night poker sessions. Hickok drunkenly shot out a stage light during one performance.
Another (possibly apocryphal) story has him knocking out every single person in a particularly unfriendly bar in New York.
Hickok only stayed with the production a few months before returning home.
Two years later he was shot dead during a poker game at a saloon in Deadwood - a fitting end.
The hand he drew just before he was killed, two-pair black aces and eights, is known as dead man's hand.
A few years later Cody would establish his hugely successful touring revue Buffalo Bill's Wild West.
The lot last sold for $35,850 at Heritage Auctions in 2011.
We have this signed photograph from sharpshooter Annie Oakley, who starred in Buffalo Bill's show.
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