1. A method of production planning that considers multiple due dates for providing the same resource to the same demand item, wherein said multiple due dates comprise a first date when said resource can be provided to said demand item, and a later second date when said resource must be provided to said demand item, said method comprising: creating, from a single part number, a first artificial part number associated with providing said resource to said demand item by said first date, wherein said single part number bins to said first artificial part number; creating, from said single part number, a second artificial part number associated with providing said resource to said demand item by said second date, wherein said single part number bins to said second artificial part number; performing, by a computer, production planning for both said first artificial part number and said second artificial part number to determine when said resource can be provided to said demand item; selecting one of said first artificial part number and said second artificial part number to satisfy said demand item; and reinstituting said single part number for the selected artificial part number.