Actually 'The Travelling Companions', painted in 1862 by the rather curiously named Augustus Leopold Egg (1816-1862). I've always found this a slightly odd painting, with the identical outfits and hats, though I suppose it must show a pair of twins. As you can see from his dates, he died young. He was a friend of Dickens, who described him as "dear gentle little fellow," "always sweet-tempered, humorous, conscientious, thoroughly good, and thoroughly beloved'.