Documents folder seems to contain hidden folders when using roboco

I am using Vista Home Premium. I have been using robocopy to backup the
directory c:\users\username\documents. I have noticed that when I use
explorer to check the size of this directory it says 8.1 GB. When I attempt
to copy it using robocopy "C:\users\username\documents" j:\ /mir /v
/log:c:new.txt, I find that two things happen:
1. The log file shows that in addition to copying all the documents in the
documents folder, it also copies all the files in the C:\users\username\music
folder as well (ironically to a folder on J with the old XP style
structure......J:\user\username\documents\my music). This is an additional
9GB.
2. on the J: drive, it shows 17 GB being occupied; however, I cannot find
any of the files from the c:\users\username\music folder that the robocopy
log file says were copied (and must be there since J is showing an additional
9 GB of data that can't be accounted for.
Is Vista somehow hiding folders in the \Documents folder that then get
picked up by robocopy? How come I cannot access the copied filed from \Music.
When I migrated from XP to Vista, I manually copied the music files into the
\Music folder, I did not use any type of auto migration software.
Thanks

 

Vista uses junctions to link certain folders (such as Music) to the documents
folder. You can use the RoboCopy "/XJ" argument to exclude following
junctions.