Slice, I must repeat what I said: I have no need to export / import. In fact, I will never export or import anything in Edge.
I set up Windows with a local account, then first thing I do is to sign in to Store with my main MS account, which then automatically signs me in to all MS services and apps. I do not switch to MS account in Windows, continue using a local account which can be seen for instance in Settings app. Mine does not show "Switch to local account" which it would show if signing in to Windows with an MS account, it shows "Stop signing in to all Microsoft apps automatically":
Short: I use local account but have connected it to all MS services and apps.
OK, this done, I enable sync in Settings, sign in to Bing and Outlook.com in Edge, and finally check that Edge syncing is enabled and using correct MS account in Edge settings:
I have absolutely no need to export / import anything, nor will I get duplicates.
Kari