Excel vba merge cells based on duplicate cell data

[p45cal]

Merged cells are a big pain with vba.
I can't arrange for the middle cell of 3 merged cells to contain the value (as in your picture), Excel only allows the top left cell of a merged range to contain the value.
In the macro below, I've arranged for the 4 rightmost columns to be merged in the same way as the first column, and each merged area will take on the value of the top cell in that area, losing any values that are different in the other cells (if they're all the same, consider removing duplicate rows instead; it's built in and faster).
There should be no merged cells before you start.
There are entire lines of code commented out which I used as debug lines which can be deleted.
According to your picture the data body seems to start in row 3, hence the line rw = 3 'start row in the code.

Sub blah()
    lr = Cells(Rows.Count, "M").End(xlUp).Row
    rw = 3    'start row
    Set myRng = Range(Cells(rw, "M"), Cells(lr, "M"))
    ' myRng.Select
    Set TopCell = myRng.Cells(1)
    Set BottomCell = myRng.Cells(1)
    myVal = TopCell.Value
    For Each cll In myRng.Cells
        If cll.Value = myVal Then
            Set BottomCell = cll
        Else
        Range(TopCell, BottomCell).Select
        If TopCell.Row <> BottomCell.Row Then
            ' merge:
           For ofst = 4 To 0 Step -1
                ' Range(TopCell, BottomCell).Offset(, ofst).Select
                Merge Range(TopCell, BottomCell).Offset(, ofst)
            Next ofst
        End If
        ' cll.Select
        Set TopCell = cll
        myVal = TopCell.Value
        Set BottomCell = cll
        End If
    Next cll
    Range(TopCell, BottomCell).Select
    If TopCell.Row <> BottomCell.Row Then
        ' merge
        For ofst = 4 To 0 Step -1
            ' Range(TopCell, BottomCell).Offset(, ofst).Select
            Merge Range(TopCell, BottomCell).Offset(, ofst)
        Next ofst
    End If
End Sub

Sub Merge(Rng)
    ' Rng.Select
    With Rng
        .VerticalAlignment = xlCenter
        Application.DisplayAlerts = False
        .MergeCells = True
        Application.DisplayAlerts = True
    End With
End Sub