This is caused because Deduplication is set on the volume AND the backup type under the NDMP job settings is set to VBB (also known as NVB (NDMP Volume Backup)).
EMC does not support restoring individual files from a NVB of a Deduplication-enabled volume. Please read pdf page number 14 for more clearification:
Change the NDMP backup method in the job settings from VBB to DUMP, if individual file restore is required.
Note: The only way to restore an NVB backup of a deduplicaton-enabled volume, is to do a full destructive restore of the volume.