Addictivetips published a tutorial about how to merge two folders on Windows 10.

How to merge two folders on Windows 10

Copying and moving files on Windows 10 has changed. The change is subtle but exceptionally useful. You’ll notice it when you’re copying a file or folders with the same name to a new destination. When you move a file to a location that has another file with the same name and extension already present, Windows 10 will ask if you want to replace the file in the destination or keep it. If you choose to keep it, the file will not be moved. 

How to merge two folders on Windows 10