Bonjour,
à tester,
Sub Test_compilation()
Dim sh1 As Worksheet, sh2 As Worksheet
Set sh1 = Sheets("Feuil1")
Set sh2 = Sheets("Feuil2")
rw1 = sh1.Cells(Rows.Count, "A").End(xlUp).Row
For i = 2 To rw1
n = Application.Match(sh1.Cells(i, "A"), sh2.Range("A:A"), 0)
If Not IsError(n) Then
sh2.Range("B" & n) = sh2.Range("B" & n) + sh1.Range("B" & i)
Else
rw2 = sh2.Cells(Rows.Count, "A").End(xlUp).Row + 1
sh2.Range("A" & rw2 & ":B" & rw2) = sh1.Range("A" & i & ":B" & i).Value
End If
Next
End Sub