Now, it's clear that phone makers are cooling the hype around folding phones after Samsung's Galaxy Fold issues. It's not hard to imagine why: Making a single flexible screen that can withstand the torture of daily use is incredibly difficult. Just look at the insane warnings Samsung put on its revamped Galaxy Fold: keep it away from coins, keys and cards, you know things also in your pockets. Don't put too much pressure on the screen, even with your nails. And be sure to keep the fold away from small particles like pocket lint! And don't forget, never twist your phone the wrong way, a limitation of every foldable phone.

Those issues are less of a problem on devices like the Surface Neo and Duo. Instead of stressing the screen directly when opening and shutting them, the hinge takes the brunt of that force. You can also fold both Surface devices a full 360-degrees, allowing them to move from a booklet orientation to just a single screen when you need something more compact.

That's something OLED folding phones just can't do without serious compromises. The Galaxy Fold relies on an awkward and skinny external screen when its closed. Huawei's Mate X, meanwhile, has its entire folding screen on the outside. While that makes it usable when it's "closed," it also leaves your precious display completely vulnerable. That's particularly bad, since folding screens can't be covered in glass -- turns out, it doesn't really bend well -- and you likely won't be able to cover them easily with cases.

Simply put, using two separate displays is a huge win for durability. When they're closed, the Surface Neo and Duo feel a bit like jewelry cases protecting their precious screens. And even though their exteriors are also covered in Gorilla Glass, Microsoft reps say they're still strong enough to take a few tumbles. They couldn't use metal backing since that tends to interfere with antennas. And that's not something you'd want when you're pushing LTE on all these new devices. And given that they're relatively radio transparent, both could conceivably be upgraded with 5G down the line without changing the cases much.

"We experimented with folding screens as everyone else has, but then we came across this insight of having information on two separate screens and how much this helps the human brain show a flow of tasks," said Ralf Groene, Microsoft's head of industrial engineering, in an interview with Engadget. "And we were like, well why don't we make just two screens? It's much more flexible, more reliable, and you get into more positions."