Bonjour,
solution via une macro à tester, la macro crée une nouvelle feuille avec le résultat.
Sub transpose2col()
Set ws1 = Sheets("taf")
Set ws2 = Worksheets.Add(after:=ws1)
dc1 = ws1.Cells(1, Columns.Count).End(xlToLeft).Column
k = 1
For i = 1 To dc1 Step 2
dl1 = ws1.Cells(Rows.Count, i + 1).End(xlUp).Row
For j = 2 To dl1
k = k + 1
ws1.Cells(j, i).Copy ws2.Cells(k, 2)
ws1.Cells(j, i + 1).Copy ws2.Cells(k, 3)
ws1.Cells(1, i).Copy ws2.Cells(k, 1)
Next j
Next i
Set ws1 = Nothing
Set ws2 = Nothing
End Sub