Mange's and Steam on Windows Insider Program

It's been determined that the game executable is date (and time) checking the XML files to determine which is the newest.

So, in the first pic above, we can see the Steam installation of SMR. All files will have the date of the install by Steam. The original and GOG versions have a dates from 2006 when SMR was published. This explains why original and GOG users never have a problem with new maps or Mange's.