A Salesforce change in how fields are queried impacted LCRM Classic Gift Batch tools.

To resolve the issue, you may reach out to Luminate CRM Support to determine which field is causing the issue, or View Debug Logs to look find it on your own. After you have determined the field causing the issue, you must rename the Field Name (not Label Name) of the custom field that is causing the error. The following Knowledge Articles contain additional information: 

Managed and unmanaged fields with the same name

Error: 'Duplicate field selected' for Contacts merge in NPSP