I know this is a SQL Server 2005 related post, but when using the wizard for moving a database from SQL 2012 to SQL 2014 we received the same error. After doing some research, I found this:

https://connect.microsoft.com/SQLServer/feedback/details/252471/ssis-errorcode-column-in-source-table-causes-duplicate-errorcode-to-be-introduced

We found out that if you have a column in any of your tables named [ErrorCode] or [ErrorColumn] it will throw an error. We re-named the fields and everything ran fine. Apparently, this is a feature of the wizard.