How to copy repeated numbers

Does anybody know how to copy a repeated number from one cell to another.
Example:
I have a list of numbers (1,2,3,4,5,6,1,2,3,7,1,2) on cells A1 thru A12. As you can see numbers 1,2 are repeated on two ocassions and 3 is repeated once. How can I "automatically" populate cell B1 with the repeated number 1, cell B2 with the repeated number 2 and cell B3 with the number 3. Also, "automatically" populate cell C1 with the second repeated number 1 and cell C2 with the second repeated number 2.
So, basically I just want to put in numbers in column A and "automatically" populate the other columns as the numbers repeat. Thank you.

See attachment for example.

Hi

Try the following code, which should work for any number of repeats.

Sub Dup_copy()

Dim a As Integer, b As Integer, c As Integer, lastrow As Integer

Let lastrow = Range("a65536").End(xlUp).Row

For a = 1 To lastrow

Let b = Application.CountIf(Range(Cells(1, 1), Cells(lastrow, 1)), Cells(a, 1).Value)
If b > 1 Then

For c = 2 To b

If Application.CountIf(Columns(c), Cells(a, 1).Value) = 0 Then
Let Cells(1, c).Offset(Application.CountA(Columns(c)), 0) = Cells(a, 1).Value
End If

Next c

End If

Next a
End Sub

Regards

Jeff