Mr Duncan was an investor in Cascade Coal, a mining company that bid successfully for one of the licences at Mt Penny, in the Bylong Valley.
Last week Justice Peter Garling ordered that the proceedings against the commissioner be expedited and that documents be handed over by both parties.
In a brief appearance at the NSW Supreme Court on Tuesday, Matthew McLennan, appearing on behalf of the NSW premier, handed up documents from the NSW Department of Primary Industries (DPI).
He said the documents had been given to them "in confidence" by the DPI and the department may wish them to remain so.
The issue of privilege in relation to these documents will be discussed on Thursday morning, before the hearing on March 22.