Merge Duplicate data

Im looking to save some time here.. I have over 10000 rows in excel which need to be merged

i.e.
MODEL,QTY
1000,5
2000,2
3000,3
2000,2

and i want to run a macro to get this result
1000,5
2000,4
3000,2

I would like to remove duplicate model numbers but merge(add) the QTY field

I did some research and came up with this macro.. but it only removed duplicate data... any help with a modification? or a better macro?

Sub DelDups_OneList()
Dim iListCount As Integer
Dim iCtr As Integer

' Turn off screen updating to speed up macro.
Application.ScreenUpdating = False

' Get count of records to search through.
iListCount = Sheets("Sheet1").Range("A1:A100").Rows.Count
Sheets("Sheet1").Range("A1").Select
' Loop until end of records.
Do Until ActiveCell = ""
   ' Loop through records.
   For iCtr = 1 To iListCount
      ' Don't compare against yourself.
      ' To specify a different column, change 1 to the column number.
      If ActiveCell.Row <> Sheets("Sheet1").Cells(iCtr, 1).Row Then
         ' Do comparison of next record.
         If ActiveCell.Value = Sheets("Sheet1").Cells(iCtr, 1).Value Then
            ' If match is true then delete row.
            Sheets("Sheet1").Cells(iCtr, 1).Delete xlShiftUp
               ' Increment counter to account for deleted row.
               iCtr = iCtr + 1
         End If
      End If
   Next iCtr
   ' Go to next record.
   ActiveCell.Offset(1, 0).Select
Loop
Application.ScreenUpdating = True
MsgBox "Done!"
End Sub

Thanks guys