If you use Form.FlattenAllFields() and your pdf form has duplicate field names, this method will remove the data from the duplicated field.
My work around is:
foreach (var field in pdfDoc.FieldNames)
pdfDoc.FlattenField(field);
Would you please share your sample PDF document with us so that we can test the scenario in our environment and address it accordingly.
Can you provide me with an email address?
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