I don't see why they couldn't have just been brothers? Was there some special significance to them being twins? It just seems that it needlessly complicated the filming (using the same actor). I'm sure creating the "twins" effect is much simpler nowadays versus the days of the original "Parent Trap". I just didn't see the importance of going through any trouble for something that seems so insignificant.
shareWell, the short answer is that they had to be twins in the film because they were twins in the book.
But the reason it's important to the story is that Simon is kidnapped by goblins who mistake him for Jared (because they are identical). This event is, of course, what convinces Simon (and later Mallory as well) that Jared was telling the truth about the creatures in Spiderwick's book. If you take out the boys being twins, you'd need to change a large chunk of the story.
^ yeah but that wasn't the case in the film though? When Simon is kidnapped I don't remember the goblins thinking he was Jared.
shareThey did. After they discover that Simon doesn't have the book and release him, they have this exchange.
Mulgarath: "You failed me Redcap."
Redcap: "There are two humans boys with the same faces...Jared and not-Jared. We took the wrong one."
Then Mulgarath tells Redcap to "find the Jared and get the book."
So Mulgarath and the goblins know that Jared has the book and came after him, but snatched his brother by mistake.
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