Sub geauxin()
Dim Vin As Variant, Vout As Variant, i As Long, S As Variant, ct As Long, k As Long
Vin = Range("A2:B" & Cells(Rows.Count, "B").End(xlUp).Row).Value
ReDim Vout(1 To 20 * UBound(Vin, 1), 1 To 2)
For i = 1 To UBound(Vin, 1)
S = Split(Vin(i, 2), ", ")
For k = ct + 1 To ct + UBound(S) + 1
Vout(k, 1) = Vin(i, 1)
Vout(k, 2) = S(k - 1 - ct)
Next k
ct = ct + UBound(S) + 1
Erase S
Next i
Range("D:E").ClearContents
Range("D1:E1").Value = Range("A1:B1").Value
Range("D2:E" & UBound(Vout) + 1).Value = Vout
End Sub