The Section may, with written approval by the Director, allow an agency to participate in, sponsor, conduct or administer a cooperative agreement for the procurement of professional services with 1 or more public procurement units either within this State, with or within another state, or with a consortium of other states in accordance with an agreement entered into between the participants. Such agreement may include material and/or nonprofessional services with professional services. The other provisions of this subchapter shall not apply when an agency participates in an existing cooperative agreement for the procurement of professional services with a contractor holding a current contract as part of such cooperative agreement.