Thanks for the solution.
But I am reading them from QVDs.
The problem actually started this way,
I had several Modified Date for the same "stage" of the Item in the data model. Stage,here are like pending stage, design stage etc.
But my user is actually using the last. modified date. So I loaded the max(Modified Date) with the Item Id, which suppossedly should have given me single records for each item, but now it seems that even max(modified date) is repeating.