cimorene

Agatha Christie has a couple of stories where she obviously revisited an idea later, resulting in two very similar stories, such as "The Plymouth Express" and "The Mystery of the Blue Train" or "Triangle at Rhodes" and "Evil Under the Sun". I've just encountered the first near-repeat of this type in Nero Wolfe with "Man Alive", the 1st of 3 stories in the collection Three Doors to Death, which is strongly reminiscent of The Red Box. It's funny that it's a short story though, since usually writers rewrite earlier short stories as novels, not the other way round.