The LG V20 (VS995) international version is dual sim. But also has removable battery, tough outer case, good cameras, and is big. It does not cover ATT LTE bands 17 and 30. I am considering the NA version and just go single sim.
https://www.amazon.com/dp/B01M4MY4RY
and a 10,000 mAh extended battery that can go on the back
https://www.amazon.com/Battery-ZeroL...lg+v20+battery
You don't find many replaceable battery phones any more. Comes with Nougat out of the box.