Check if a table contains duplicate records
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I have a datatable with two columns FromDate and ToDate , which are in string format.
I want to check if there are any duplicate records in my table.i.e 
From Date       To Date      
9/01/2012    9/16/2012   
8/23/2012    8/24/2012   
8/25/2012    8/25/2012   
8/5/2012     8/6/2012    
8/26/2012    8/27/2012   
9/15/2012    9/23/2012
The table contains duplicate records as their date range is mapping for 
From Date       To Date      
9/01/2012    9/16/2012   
9/15/2012    9/23/2012
It should return false.
Help would be appreciated.