Be aware that some DDL statements issued by a user cause Oracle to internally execute one or more other DDL statements. If you want to reapply SQL DDL from the SQL_REDO or SQL_UNDO columns of the V$LOGMNR_CONTENTS view as it was originally applied to the database, then you should not execute statements that were executed internally by Oracle.
If you execute DML statements that were executed internally by Oracle, then you may corrupt your database. See Step 5 of "Example 4: Using the LogMiner Dictionary in the Redo Log Files" for an example.
To differentiate between DDL statements that were issued by a user from those that were issued internally by Oracle, query the INFO column of V$LOGMNR_CONTENTS. The value of the INFO column indicates whether the DDL was executed by a user or by Oracle.
If you want to reapply SQL DDL as it was originally applied, then you should only re-execute the DDL SQL contained in the SQL_REDO or SQL_UNDO column of V$LOGMNR_CONTENTS if the INFO column contains the value USER_DDL.