Merging/importing PDFs with duplicate field names can create one logical RadioButtonField containing widgets from multiple source field nodes. The first node initializes its widget options. Reused duplicate nodes can add additional widgets without assigning RadioOption instances.

The widgets then contain valid "/Off" appearance states, but their model Option property is null. During export, FieldPropertiesExporter accesses widget.Option.Value, causing a "NullReferenceException: Object reference not set to an instance of an object."