I'm trying to perform an upsert using the Dataloader. Basically, I have records with duplicate ID numbers. This is not a mistake (but probably a source of larger data integrity issues). They are two parts of the same object and I want to keep them both.
Naturally, dataloader doesn't like this and returns the error:
Duplicate external id specified...
In setup for this object, the box
do not allow duplicate values is not checked.
Any advice for me?