I agree with r937, it doesn't make much sense to store the same value twice in the same row, just formatted differently. That sounds like a job for the presentation layer.
Having said that, it doesn't matter what value you have in the third column, your query won't work because you are using an aggregate function and the third column isn't, and can't be, in the group by clause. Instead, you need to use a correlated subquery:
SELECT RID, REPORT_DATE, REPORT_DATE_FORMATTED
FROM test.sample AS s
WHERE (REPORT_DATE =
WHERE (s.RID = RID)))
In my tests, this returned the expected result set.