Hi,
The cause for this issue is because you have a transaction where the Transaction source, Posting date, Vendor ID, Control Type and Voucher Number all are same.
If you want to check which transaction exactly is duplicated, please run SQL Profiler, from Tools Menu of SSMS and click SQL server profiler Connect to the server and in the Trace properties window, click on Events Selection unselect all events and later select all for Errors and Warnings, Stored procedures and TSQL --> then click on RUN button once the trace runs in TEXT DATA column you will be getting the Values with the Error for the transaction for which exactly the error is appearing. please verify the transaction.
hope this helps,
Regards,
SantoshG
