Duplicate Defects means 
The same type of defects that are present in defferent 
places of application bcoz of copy,paste operation of code 
during the code development process.
For example if you take one application it has 9(lets say)
screens.
But the 9 screens have some identical properties/features.
The developpers will write a piece of code then this code 
will be copied and used where ever they need.

During the process of Test case execution if we find any 
bug we used to enter the the failure result in test case
and we assign a bug id for that.

we know that we used to write test case such that for each 
and every functionality there must be at least one test 
case.

If we find the bug for first time we enter the bug 
description in defect report and we assign a bug id.
if we fined the same bug again already entered bug will be 
present in the test case result column.

byee 
Rajendra 
rajendra_penumalli@yahoo.com
9885162742

HI


   Raising the Already existed defect which is in open
   condition in the defect report log



   sun_ramprasad@yahoo.com
   9940314706

Its nothing like fiding a duplicate defect. When a person 
logs a defect, and unknowingly another person also logs the 
same defect, it is said to be a duplicate defect