How to trace transations occurring at same time

We have a table, in which two transactions occurred at the same time, at the same second. Now the issue is we need to know which transaction precedes the other. Because at CPU cycle level both cannot happen simultaneously.

The following is the table data:

POLICY_NO	Date	BAL_BEFORE	BAL_AFTER
104	28/12/2009 07:00	29.305575	29.288479
104	28/12/2009 07:00	29.311511	29.305575
104	29/12/2009 11:13	32.285601	33.728863
104	28/12/2009 07:00	16.710067	16.700319
104	28/12/2009 07:00	22.44572	22.432626
104	29/12/2009 11:15	48.625391	50.507892

Note that the first 2 rows has same time stamp to very second level.

The database is Oracle 10g R2.

Thanks and Regards.

Abdullah