Delete Cells With Repeating Values

[Gammazoni]

Hello, I have a code like that, which has been using by me, but now I need another one, which won't differ a lot, I hope. Please, analize it, I believe that here I'll find somebody with large luggage of experience. Please, write any suggestions you have.

Sub test() 
    Dim ws As Worksheet, a, i As Long, ii As Long, b(), n As Long, w(), e 
    With CreateObject("Scripting.Dictionary") 
        For Each ws In Worksheets 
            With ws.UsedRange 
    a = .Value 
    .ClearContents 
End With  
            Redim b(1 To UBound(a, 1) * 2, 1 To UBound(a, 2)) 
            For ii = 2 To UBound(a, 2)  Step 4 
                For i = 1 To UBound(a, 1) 
                    If Not IsEmpty(a(i, ii)) Then 
                        If Not .exists(a(i, ii)) Then 
                            .Add a(i, ii),  Array(a(i, ii - 1), a(i, ii), a(i, ii - 1), a(i, ii)) 
                        Else 
                            w = .Item(a(i, ii)): w(2) = a(i, ii - 1): w(3) = a(i, ii) 
                            .Item(a(i, ii)) = w 
                        End If 
                    End If 
                Next 
                For Each e In .items 
                    n = n + 2 
                    b(n - 1, ii - 1) = e(0): b(n - 1, ii) = e(1): b(n, ii - 1) = e(2): b(n, ii) = e(3) 
                Next 
                n = 0: .RemoveAll 
            Next 
            ws. Range("a1").Resize(UBound(b, 1), UBound(b, 2)).Value = b 
            n = 0 
        Next 
    End With 
End Sub 

I was using it to delete unnecessary coordinates from two columns, where first column is named 'x' (for arguments) and another one named 'y' for values. I mean I have a diagram, which is described by many coordinates. I need to delete these coordinates, which aren't useful for this diagram, because one straight line in diagram may be described by only two coordinates describing two points. Or I will say it more clearly - every line is described by linear function. Please check third row under title 'Before'. These columns are repeating after every next two empty columns. So after column A&B we should see E&F etc. Program above is used to delete these coordinates, where arguments have increasing values n+1, where n is any positive number expect zero. Values for each arguments repeat a few times, so it would be looking in Excel like that:

Before:
A B
1. 1 1
2. 2 2
3. 3 2
4. 4 2
5. 5 3
6. 6 3
7. 7 3
8. 8 3
9. 9 4
10. 10 4
11. 11 5
12. 12 6
13. 13 6
14. 14 6
15. 15 7
16. 16 7
.. .. ..

After:
A B
1. 1 1
2. 1 1
3. 2 2
4. 4 2
5. 5 3
6. 8 3
7. 9 4
8. 10 4
9. 11 5
10. 11 5
11. 12 6
12. 14 6
13. 15 7
14. 16 7
.. .. ..

But I would use the code for other purpose. I put now a force on two aspects - if there will be only one-column interval between columns with coordinates and another thing - if the scheme will look now inversely - instead X's will be Y's and vice versa, then I will see diagram in horizontal position. But I find a problem, because I don't know how to change the code. Please, help me anybody.