I think this theory has good heart, but the show did make a point of showing Lapidus mentioning that the pilot shown in the wreckage wasn't who the TV reporters claimed he was.

That should put the kabash on the plane mysteriously replicating at both the Island and trench. I really think the fake 815 was planted so that the search for the survivors would cease.

to Folie au Deux's point about Locke's dad:
I don't think he thought he was kidnapped (although looking at it in hindsight, he most likely was). I believe he thought he was dead.

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Abaddon