[TYPO3-dam] Why do I see the same media folder with the same uid several times?

[Uschi Renziehausen]

Hello folks,

i am a dam newbie. I am working with 4.2 branch of typo3 and dam from 
svn. Now, in my pagetree, I see multiple media folders all pointing to 
the same id (418). If I click on those folders, I see exactly the same 
contents in list view. How comes that I see those multiple folders, and 
how can I 'repair' this?

Regards, Uschi