Update location code using HSDL

I am trying to update a location code for an existing location using HSDL.

I am aware that the location code is a key and so based on the spreadsheet loader restrictions can't be updated without creating a separate loader for updating existing records. I have therefore created my loader using the Location business object and have selected to use a surrogate ID so that the location ID is the key.

My field for the surrogate ID has a LOV associated to identify the correct location that needs to be amended.

The loader successfully updates the fields that have been included with the exception of the location code. When trying to update this field, I get the error 'The address type MAIN already exists for this location. Verify that address information for the address type doesn't exist for the time period.'