ListView Problem without saving in DB Acces Using VB 6.0

Hello Guys.. I have a Code For Saving Item in ListView But My Problem is What If My First Column Same BarCode into Example:
Barcode QTY
001------5

And I add Another Item

Barcode QTY
001------5
001------5

My Point is What Should I do And How to Do The Quantity of two Itme Added in One Then They BEcome
Barcode QTY
001------10


This is My Code for Adding in Listview

ListView1.ListItems.Add , , lblrp.Caption
ListView1.ListItems.Item(ListView1.ListItems.Count).ListSubItems.Add , , txtCode.Text
ListView1.ListItems.Item(ListView1.ListItems.Count).ListSubItems.Add , , txtproductname.Text
ListView1.ListItems.Item(ListView1.ListItems.Count).ListSubItems.Add , , txtqty.Text
ListView1.ListItems.Item(ListView1.ListItems.Count).ListSubItems.Add , , txtprice.Text
ListView1.ListItems.Item(ListView1.ListItems.Count).ListSubItems.Add , , lbltotal.Text
ListView1.ListItems.Item(ListView1.ListItems.Count).ListSubItems.Add , , MDIForm1.lbldate.Caption