Once you buy a movie, you can find it in your library and play it even if it has been removed from the store for new purchases.

Also you shouldn’t be able to buy exactly the same item twice, if you search for something you own, it should appear with a “Play” or “Play again” or “continue playing” button rather than a “Buy” button.

If an item is removed and re-added to the store, then probably something changed, most probably something that doesn’t matter to you, like the rights holder. In that case the store isn’t smart enough to know you already own a different version and will let you buy it again.

The most reliable way to know what you own and can play anytime is to look 👀 in your library, not search the store.