Delete Row Based On Cell Below

I currently have a spreadsheet with circa 50,000 lines with info regarding our websites at work. In every row, column "A" contains a unique reference number.There eill either be 1 row for this reference number, or there will be 2 rows. there will never be more than 2 rows for each reference. I wanted some code to say that if theres only one row, then delete it but if the if the cell underneath it is the same then its ok. I tried the following but it deletes the row anyway, supposing the cell under it is the same or not

Sub test()
Dim icell
icell = ActiveCell.Offset(1, 0).Value
Range("A1").Select
Do
If ActiveCell.Value = icell Then
ActiveCell.Offset(2, 0).Select
Else
ActiveCell.Rows.Delete
End If
Loop Until ActiveCell.Value = ""
End Sub