This is not relevant, has nothing to do with the hashbang, and is not really a bug. It's an SEO feature. Most websites do this, including big names like Amazon for instance: http://www.amazon.com/The-Ultimate-Hitchhikers-Guide-Galaxy/... is the same as http://www.amazon.com/dp/0345453743 (and also the same as http://www.amazon.com/The-Holy-Bible/dp/0345453743).