When you have two controllers and only the second has a volume, Storage Viewer shows the volume on both controllers. If the first controller has a volume or both controllers have volumes, then this is not an issue.
If you see this condition please contact Oracle support services to get a firmware update for your 16 disk backplane. The new firmware will zone your backplane and prevent this issue from occurring.
This is an Oracle ILOM issue, which might be fixed in a future ILOM release.