Flashback archive is inserting data even no data changed after update statement

Question

I have enabled Flashback archive on a table. Oracle inserts data in Flash back even if no record is changed in the table after updating a record.

For example

Update Dept set DEPTNO = '10' WHERE DEPTNO = '10';

When i use flashback query to extract all records it shows 1 record is added.

SELECT  versions_startscn, versions_starttime,
       versions_endscn, versions_endtime,
       versions_xid, versions_operation,
       dept.*
  FROM dept
  VERSIONS BETWEEN  SCN MINVALUE AND MAXVALUE;

Is there any setting for FlashBack Archive that it store only changed records.?