Export Participants and Export Contributions drop records when multiple rows belong to the same Contact

When there are multiple Participant records for the same contact record and one Export Participants, the resulting CSV file only contains one record for each contact. See:
http://forum.civicrm.org/index.php?topic=20873

I replicated same behavior for Export Contributions and Expot Memberships.

This is a regression bug that ALSO exists in the latest 3.3 branch (3.3.7) but works properly in 3.2 branch. I suspect that a recent change in 3.3.7 which was merged to 3.4 and 4.0 may have caused this bug.