Inventory Item Code - Modification @ PO screen

Recently our  Inventory supervisor  come with a issue - for  a single item code - he is getting different  item description on different  purchase order .

Example :

Item Code  : CableTie    -  Item Description : SUPPLY OF CABLE TIE 150MM

In One PO for the same item code the description is  : SUPPLY OF CABLE TIE 250MM

on another PO the item description  is : SUPPLY OF CABLE TIE 350MM

All all these  items  specification and price are different. . As we use  average item cost concept - we are facing problem due to this.

In  PO creation screen system allows  PO user to change description.    System should allow to change the description at  PO creation level.