Unless specific authority has been granted by the Commissioner, all funds received (except cash needed to replenish vault cash at levels authorized by the board of directors) shall be deposited in accordance with Section 14406 of the Financial Code by the credit union within 48 hours of their receipt (exclusive of Saturdays, Sundays and holidays), provided, however, that receipts in the aggregate amount of $1,000 or less need not be deposited more often than once each week. The deposit slips shall be prepared in duplicate, the duplicate copy to be retained by the credit union as a part of its accounting records.