In some cases it is possible that duplicate stores exist in the underlying native representation, for example duplicate mount points in a mount table. This can result from a bad configuration, auto-mounting, etc. Currently it is an error flagged by java/nio/file/FileStore/Basic.java to have duplicate FileStores in the getFileStores returned Iterable. It should be investigated whether it would be better to detect duplicate stores (mount points) in the Java libraries and automatically filter them out. In this case the duplicate check in Basic.java could be removed, as could be checking the output of 'df' for duplicates on Unix systems.