Oracle Error Message
RMAN-06971: NEWNAME ‘string’ for tablespace must include %f or %U format
Reason for the Error
The newname in SET NEWNAME FOR TABLESPACE did not include a format specifier to produce different newnames for the datafiles.
Solution
Include %f or %U in the newname or use SET NEWNAME FOR TABLESPACE … TO NEW to ensure datafiles get different datafile names.