As to the app "Duo" it is a Google app. It is actually called "Google Duo" (although the app my only say "Duo" on your device. It is a video chat mobile app developed by Google.
As to the ones that don't have an uninstall. Without rooting the device, which I so would not recommend as you risk bricking the phone, there is no real way to remove them.
That said, disabling them works great. While it won't remove them, which means it wont free up space that they take up, it will make them not effect how you use the device. Personally I wish carriers and manufacturers would stop making unnecessary apps not removable, but they likely get money in doing so.
Disabling them is your best option.