When I add a FileSystem Directory View in order to install PloneCalendar in  my portal_skins Folder, I choose the Id: PloneCalendar
no problem the  Filesystem Directory View at  portal_skins/PloneCal is well populated
but I can notice now  in the directory plone_3rdParty a new directory created at the same time 
2003-09-26 13:01
it is called  PloneCalendar-1.0.2  (despite the fact that I have renamed in my file system the directory PloneCalendar-1.0.2 to PloneCalendar) (There are currently no items in PloneCalendar-1.0.2)
and ...
all my skins but Custom seem to have been modified  Last Modified Time 2003-09-26 13:01
Is it supposed to happen?
Shall I add that I "loose" skins every timeI update Plone?