Your error may look similar to this:
Validation error. Data Flow Task: DTS.Pipeline: The package contains two objects with the duplicate name of “output column “ErrorCode” (180)” and “output column “ErrorCode” (13)”.

In my case, here’s how I fixed it:
On the task(OLE DB Source) that gave me the error, I went into the advanced editor. Go to the “Input and Output Properties” tab and select the Error Output Columns. I simply changed the name of the second instance to ErrorCode2 and it worked for me. It may be better to actually rename your column in the table but that requires more work. I guess it’s possible that this could affect your error logging but for my case it did not.

One fix is to save the file as .sql and browse to it from within the Execute SQL task. Once I tried this I noticed that my last few lines were finally there. If you know of other ways around this please feel free to share.