Why no one makes a dual display tablet?

So I have been traveling working on mobile devices like tablet and laptop a lot lately and I am having a hard time working with the small screen especially when I need to study multiple documents and drawings at once.

So the idea of a book-like dual display tablet 8"-10" in size that also works like a laptop when put into horizontal position crossed my mind.

With dual display, I would have space to at least display 2 documents at once that minimize the need to for me to switch the documents around. I would have more space as well for typing out emails and doing some simple word documents. I would also able to have 1 screen displaying the drawings I need to study while making comments on the other screen.

I make a doodle of what it would looks like as well, I just wonder why no one ever thought of making something like this. It would make my life much easier.

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