So many things to wonder about how a HHB film or series would be able to do Cor and Corin as twins.

Then there's hair color. It has been common for Narnia films or series to depict the characters with hair color that is different than in the books.  In the books, Susan is described as being dark haired and Lucy is described as being blond. Yet in the BBC, their hair color somehow got switched- Susan is blond and Lucy is dark haired.

For Cor and Corin, there's not a particular hair color I have in mind for them. It would be idea to portray them as blondes, as described in the book. Though they could end up with different hair colors, maybe a ginger. I think portraying them right will still count for something, regardless of what hair color they decide to go with. 

Many fan castings on myCast I have seen have casted Shasta/Cor and Corin as the same actor. I can see why this can work because they are twins, though can see this having complications with terms of filming should HHB be live action, especially when they interact with one another.

It will sure be interesting on how an HHB movie or series will end up doing Cor and Corin- twin actors or having them played by the same actor. 

And what a scene that’s going to be where they meet face to face. 

There are a lot of twins in the industry when they are younger especially on tv shows where they actually portray one character. It’s easier for production so they don’t face child labor lawsuits. But sometimes these young actors realize they don’t like acting and get out of it. It would be cool if they get real twins for Corin and Cor but I’m not against it if they do get one actor to portray both. As long the actor is good at portraying two complete opposite personalities in the same production. It should be okay.