Reptilicus

Reptilicus is the mutual title of two monster films about a giant, prehistoric reptile. A pair of Danish-American co-productions produced by Cinemagic and Saga Studio, the Danish-language Reptilicus was directed by Poul Bang and released by Saga in Denmark in 1961, while the English-language Reptilicus was directed and co-written by Sidney Pink and released by American International Pictures in the United States in 1962. They have frequently been incorrectly described as two release-versions of the same film."In every film reference book published over the past four decades, the Danish-American monster-movie Reptilicus is listed as one film, and one film only. However, in spite of sharing an identical plot, identical sets and locations, a nearly identical cast and crew, as well as overlapping use of some shots, Reptilicus is in fact two distinct films, shot in separate languages by two directors, very much in the manner of the American/Spanish versions of Universal's 1931 Dracula."

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.

Poster by Reynold Brown (Public domain).