the Deklan guy did understand the clues. they pretty much gave the impression that he understood everything.
he rembered Kyle telling him "if he had anything to tell him he would find a way"
Kyle told the story to his fake parents and left all the 'elements' he used in the story together in that box where Dek would find it.
now, i thought that clone was just another kyle model... (a terminator, perhaps)
really didn't pay too much attention to the 'xx' ... but i guess you guys might be right