How I am getting duplicate value for 'STUECKNR' field in 'QASE' table for an inspection lot number.

In 'QA32' tcode when i am going to see the inspection results for a particular inspection lot number, it is showing run time error.

So when I analyze the reason I found that there is duplicate entry for 'STUECKNR' field in 'QASE' table for a characteristic. Please suggest any reason for the above problem.