When importing data, a user may receive an exception stating 'Duplicate field  not allowed.' This occurs when the fields are not mapped correctly on the Fields tab or if two or more of the same fields are being imported.
Try each step in order until the issue is resolved:
1. In the Import parameters, select the Fields tab. 2. Click Clear Fields. 3. Click Update Fields. 4. Re-map any fields do not match up to a corresponding Raisers Edge field. 5. Add a unique extension to any field that is being imported more than once. 6. Double-check the mapped Raisers Edge fields to ensure a field is not mapped incorrectly. 7. Check the import type is being used. For example, if importing constituent attributes, a Constituent Attribute import requires each attribute to be on a separate row, but a Constituent import will allow multiple attributes on one row.