Hi Tommy,
you need to move the *.dat files stored in the directories. Please make sure to run omnidbutil -remap_dcdir before and after. If you find any issues with the command, report back.
It is expected that new DCBFs also go into the "old directory" structure. This depends on how DCDirAllocation in the global option file is configured. This does not hurt, but it should be taken into account when removing db40.
Regards,
Sebastian Koehler