When a duplicate block is found in the file system, this message is displayed:
block-number DUP I=inode-number
Inode inode-number contains a block number block-number that is already claimed by the same or another inode. This error condition generates the BAD/DUP error message in phase 2. Inodes that have overlapping blocks might be determined by examining this error condition and the DUP error condition in phase 1.
When a duplicate block is found, the file system is rescanned to find the inode that previously claimed that block.