What is the best way to notify a double posted question?

Question

This may be a dumb question about overlapping questions on sites. What is the best way to notify a double posted question? https://scifi.stackexchange.com/questions/11562/why-was-was-the-american-werewolf-able-to-see-and-talk-with-his-dead-friend and https://movies.stackexchange.com/questions/1371/in-an-american-werewolf-in-london-why-was-david-able-to-see-and-talk-with-his

Answer 1

Flag it as a possible duplicate and link to the other question. In this partiuclar instance the duplicate on sci-fi was closed so we can keep it open here.