Grrr…this one can be annoying!
But when you know how to cope with it, it’s an easy fix.
The problem: The SSIS package is failing validation with a message to the effect of “The package contains two objects with the duplicate name of “output column “ErrorCode” (123)” and “output column “ErrorCode” (456)”.
The explanation: The Data Flow source (for at least OLE DB Sources) will have a Error Output that by default will contain all the columns of the Source with two additional columns: ErrorCode and ErrorColumn.
The solution: The source column can be renamed as a last resort. This is often not practical or possible, the better solution is to rename the Error Output column. With the data flow open:
1) Choose the Data Flow Source
2) Choose Properties
3) Click ‘Show Advanced Editor’
4) Navigate to ‘Input and Output Properties’
5) Open the Source Error Output
6) Scroll to the bottom of the list and rename the last ‘ErrorCode’ column.
Thanks to: http://bturnip.com/nerdalerts/archives/146