We are having R12 instance and we use retro(enhanced). I think the overlapping will not be the case for retro enhanced.
The Problem we are facing here is ,
1) Setup for retro enhance is done
2) As there were some Awaiting records we found which got created in the initial go live period (they tried to setup retro an year back

) , we changed the status to 'C' by script.
3) Set the recorded date to 28-Nov-2011 in pay_recorded_requests as per the oracle's advice.
4) ran retro on 28-Nov-2011.
5) Users deleted back dated non recurring element entries which are not related to retro elements on 28-Nov-2011
6) The MAIN PROBLEM is , the retro notification report is picking all back dated changes (including grade and basic changes) for the above employees even from 2010.
The issue is looking so strange and difficult to debug.