This from IMDB
" Kevin Costner was originally involved with Tombstone (1993), another film about Wyatt Earp, written by Kevin Jarre. However, Costner disagreed with Jarre over the focus of the film (he believed that the emphasis should have been on Wyatt Earp rather than the many characters in Jarre's script) and left the project, eventually teaming up with Lawrence Kasdan to produce his own Wyatt Earp project. Costner then used his then-considerable clout to convince most of the major studios to refuse to distribute the competing film, which affected casting on the rival project. As it turns out, the rival film was considerably more successful. "
Almost, would have been just the one version, I for one was glad for the two....Tombstone heads above Wyatt Earp though