Sub Test()
     Dim ws As Worksheet, sh As Worksheet, m As Long, i As Long
     Set ws = Sheet1: Set sh = Sheet2
     m = sh.Cells(Rows.Count, "B").End(xlUp).Row
     If m < 6 Then MsgBox "No Headers", 48: Exit Sub
     For i = 11 To ws.Cells(Rows.Count, "A").End(xlUp).Row
         If Application.WorksheetFunction.CountIf(sh.Columns(3), ws.Cells(i, "B").Value) = 0 Then
             m = m + 1
             sh.Cells(m, "B").Resize(, 2).Value = ws.Cells(i, "A").Resize(, 2).Value
         End If
     Next i
 End Sub