The pedant in me is compelled to point out those girls aren't twins. They were about a year apart in age. It's mentioned when they're explaining the history of the hotel, and how the caretaker went mad and murdered his family.
(I'll crawl back into my box now. )
But to get more meta, the image is based on a Diane Arbus photo of twins Kubrick saw.
There came a time when the Old Gods died! The Brave died with the Cunning! The Noble perished locked in battle with unleashed Evil! It was the last day for them! An ancient era was passing in fiery holocaust!