Sub test()
tablo = Range("C4:E" & Range("C65536").End(xlUp).Row)
For n = LBound(tablo, 1) To UBound(tablo, 1)
nb = 1
For m = LBound(tablo, 1) To UBound(tablo, 1)
If m <> n Then
If tablo(n, 1) & tablo(n, 2) = tablo(m, 1) & tablo(m, 2) Then
nb = nb + 1
End If
End If
Next m
tablo(n, 3) = nb
Next n
Range("C4").Resize(UBound(tablo, 1), UBound(tablo, 2)) = tablo
End Sub