Archive_Object12_5 has Keep_Duplicates set in the schema.
Release : 14.4 CP1 Standalone
This can occur if using Oracle option to SecureFiles. Out of the box this setting does not exist.
Oracle says it Turns on or off SecureFiles Intelligent Deduplication.
DEDUPLICATE or KEEP_DUPLICATES
The DEDUPLICATE option enables SecureFiles Intelligent Deduplication; it specifies that SecureFiles LOB data that is identical in two or more rows in a LOB column, partition or subpartition must share the same data blocks. The database combines SecureFiles LOBs with identical content into a single copy, reducing storage and simplifying storage management. The opposite of this option is KEEP_DUPLICATES
Please work with your Oracle DBA or Oracle to modify this option.