Warner Bros.’ winning Die Hard formula — courageous loner foils team of hostage takers — has spawned twins at the studio: Under Siege, the just-opened Steven Seagal flick in which terrorists hijack a Navy destroyer, and Passenger 57, a November release that pits Wesley Snipes against terrorists who take over a jumbo jet. The studio’s decision to release the films so close together must have put its marketing team in a creative bind, because they’ve produced a set of very similar trailers — right down to the tag line. Both begin with the respective hijackings, as the narrator describes the ruthless terrorists. Then, just as we catch our first glimpse of the heroes, the narrator says of the villains, ”But there was just one thing they didn’t count on!” Cut to Snipes in his plane seat; cut to Seagal throwing a knife at a dart board. The trailers were recently shown back-to-back at Mann Chinese Theatre in Hollywood, inciting laughter among moviegoers. Asked whether the similarities were intentional or mere coincidence, Warner executives refused to comment.