Date Effective Row throwing error when updating existing Course Owner

Summary:

I'm loading Course Owners using HSDL and receiving the following error:

"You've provided a date-effective row that ends on 12/31/12 for an existing record that already exists with an end date of 8/19/26. The attributes provided to uniquely identify this record are already used by an existing record that ends on 8/19/26. To change the logical end date, supply the ReplaceLastEffectiveEndDate attribute with a value of Y."

Content (please ensure you mask any confidential information):

We are trying to update an existing course owner in Learning and receiving an error when uploaded via HSDL template. We have tried matching the EffectiveStartDate to the Publish Start Date that is already in the system, as well as many other dates.