I also don't like late-hour attempts to suggest that Deckard is a replicant. It cheapens Batty's finest act of forgiving him and sparing the life of his enemy who was trying to kill him.
even if Deckard is, I don't think that Roy would necessarily know - there's no indication that they can recognise their own (and if they could, that should be the basis of any test, rather than the psychological test they have to use).
