Sub Doublons()
Dim t#, tablo, resu(), d As Object, i&, n&
t = Timer
tablo = [A1:A186000] 'à adapter, matrice, plus rapide
ReDim resu(1 To UBound(tablo), 1 To 1)
Set d = CreateObject("Scripting.Dictionary")
For i = 1 To UBound(tablo)
d(tablo(i, 1)) = d(tablo(i, 1)) + 1
Next
For i = 1 To UBound(tablo)
If d(tablo(i, 1)) > 1 Then resu(i, 1) = "doublon": n = n + 1
Next
[B1].Resize(UBound(tablo)) = resu 'restitution
MsgBox n & " doublons trouvés en " & Format(Timer - t, "0.00 \s")
End Sub