If you find that Box is creating duplicate documents, Box has not been added as a "Storage Location" within the Microsoft Office Desktop app you are using.
This article covers how to add Box as a location on Office 365 Applications.
HOW TO ADD BOX ON OFFICE365 APPLICATIONS
1)IF YOU HAVE WORD OPENED, QUIT THE APPLICATION AND OPEN IT AGAIN AND CLICK ON “OPEN” AS HIGHLIGHTED IN THE BELOW SCREENSHOT.
2) CLICK ON MANAGE STORAGE
3) SELECT “BOX” FROM THE LIST, AS SHOWN BELOW
4) CLICK ON USE SINGLE SIGN ON
5) AFTER COMPLETING THE SIGN IN, CLICK ON GRANT ACCESS
6) BOX SHOULD NOW BE VISIBLE UNDER LOCATIONS ON ALL THE OFFICE DOCUMENTS AS BELOW: