[Zope] Filesystem Directory "double view"

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?