An episode a couple days ago had the same plot as the Warner Brothers Randolph Scott western "Ride Lonesome." I can't remember the name of the episode but it guest starred Andrew Duggan. The plot involved ex-outlaws trying to bring in a wanted man in order to get amnesty. Some of the dialogue from the episode was taken from the movie. That might be expected since Warner Brothers also filmed "Lawman."
The same thing can be seen in the "Cheyenne" TV series, with plots and dialogue taken from earlier Warner Brothers movies. A couple of times, the producers even put Clint Walker in the same clothes as the hero of the copied movie so that they could use long shots from the film in the TV show.
On the "Cheyenne" page, there is a forum topic dedicated to discussing the various "Cheyenne" plots and the movies that they are taken from.
A minor correction, RIDE LONESOME was a Columbia release; the common thread was Burt Kennedy, who wrote RIDE LONESOME and recycled dialogue straight from the great Scott film. I'd never seen this episode before but was able to mouth dialog right along with the characters. A bit of the music was repeated from the movie also...and I noticed the same music a few episodes ago, another Kennedy entry.
The Lawman episode "The Judge" was recycled from a 1958 Cheyenne episode called "The Angry Sky." The female characters went by the same name and a lot of the dialog is identical, but this outlaw was called "The Actor" instead of "The Black Jack."
It's a close run for who was more obnoxious as the judge: Andrew Duggan or John Hoyt, but I think Duggan wins it by an unctuous and supercilious hair.
TV westerns in general made use of a number of borrowed plots and stock episodes. With Warner Bros., however, they had a vast library of films and stories which they owned the rights to and could openly cannibalize for their works on television. Whereas somebody else's western could kinda, sorta resemble an earlier western, they could openly repackage an older work with a different protagonist in the lead role. They had the resources.
And let's be honest, people didn't have quite the access to film and television which we have today. Some individuals may have recognized plots or dialog which was familiar to them, but you didn't have people going on-line to declare an episode of Cheyenne to be a rip-off of Treasure of the Sierra Madre.
A few years ago, I saw the Bob Hope comedy The Ghost Breakers. Shortly thereafter, I saw the Dean Martin/Jerry Lewis remake from 15 years later. It was a scene by scene remake and approximately a third of the dialog was lifted directly from the original. You couldn't to a video store to pick up a copy of something made a decade or two earlier and you didn't home video.
The writers took full advantage of audience's ignorance of older adaptation, forgetfulness, and lack of access. I'm sure that such trends still continue today, but not to the same degree which they did back then.
And since westerns weren't really expected to have reruns, some of them even reused the same plots a time or two over the course of a series' tenure. One of my favorite westerns, The Rifleman, had at least four or five plots which were reused in later seasons. I could only wonder how many times a series like Gunsmoke would have reused earlier plots in its twenty year run.
For that matter, I've seen episodes of Charlie's Angels that were re-shot, scene for scene, exact same dialogue, on cable TV shows of the Nineties. Laverne and Shirley often recycled I Love Lucy scripts, as well.
When a plot looks familiar in a Warner Bros. TV show look to see if it was written by W. Hermanos (Warner Bros.). This means they are reusing a script.