We are not using simple sha256 core. The core of this chip was designed to perform multiple calculations across engines and share calculation data between chips (this is there speed come in) By calculating sha256 it split is jobs across several engines and save parts of data in memory and then computing second hash it uses that data. I can't perfectly describe this operation because myself don't know how it works. But it a lot better than simple sha256 core hash engines.
Better for what? Are you saying it has applications besides mining bitcoins and other SHA256 cryptocurrencies? If so, what are these other applications?
No I mean it's not simple sha256 core that everyone is using. It's highly revised and scaled engine which shares calculation data across other engines. Working in this it has faster hash rate than normal cores.