Moving citations to a different subfolder

I only want to move citations to a different folder. The problem is that the citation ramains also in the old folder. When I try to remove it from the old folder (both with 'delete document' and 'remove from collection') it is removed from the new one too. It is not possible to handle them as in a classical folder browser? In my opinion, the way it works is fine when you move from 'all documents' to a subfolder (http://support.mendeley.com/customer/portal/questions/1046160-citation-workflow-within-folders-in-mendeley) but not when moving between subfolders.