There was a dual screen ebook reader called Kno, that came out in 2010. https://en.wikipedia.org/wiki/Kno It had dual 14.1 inch touch screens. I recall it was priced at $2,000.
The Amazon Fire 10 inch is frequently on sale, as low as $100. You could build a cover that holds two of them, and write software that connects with bluetooth.
Google search returned something from MSI in 2010.