Have you dreamed of a dead loved one? What if you met their doppelganger in a dream? If they were a different version from another timeline, the differences might be dramatic. What if they never met your other parent, dying in battle having never married, having never reached their full potential.
If you met such a person in a dream, what message might they have for you? What gift could you give to them?
Maybe Rod Serling said it best: “Obscure and metaphysical explanation to cover a phenomena. Reasons dredged out of the shadows to explain away that which cannot be explained. Call it ‘parallel planes’ or just ‘insanity’. Whatever it is, you will find it in the Twilight Zone.”