This very thing you introduced to the discussion is all important in movie poster collecting, seaoat (I'm not one I just accidentally got Wally Yost's posters cheap to re-sell).
When a poster collector is interested in a purchase, the first thing he wants to know is when the poster was produced. Before videocassettes were introduced, it wasn't uncommon to see movies be re-released again in theaters a half-dozen times. And a poster could be and usually was produced for each subsequent release.
And then when videocassetes came on the scene, you had different posters for the videocassette release than you did for the theatrical release.
Sometimes, the later poster is identical or close to identical to the original poster. And the earlier the poster was made almost always determines the value of the poster. Sometimes the difference in value is enormous. That is especially true of the posters for the 50's sci-fi and horror flicks.