title: Excel VBA: find the union of two duplicate entries
body: <p>I am new to vba and I've got two updating columns of text &amp; I want to find the union of the two columns.</p>
  <p>For Example:</p>
  <p>+---------+---------+</p>
  <p>| A | B |</p>
  <p>|    1    |    1    |</p>
  <p>|    1    |    2    |</p>
  <p>|    1    |    3    |</p>
  <p>|    2    |    4    |</p>
  <p>|    3    |    5    |</p>
  <p>|    4    |    6    |</p>
  <p>|    4    |    7    |
  ... so on</p>
  <p>I want to write the result in a new column A, B, C ...
  With column A</p>
  <ul>
  <li>number 1, 1 to 3</li>
  <li>number 2, 4 to 4 (if not duplicate at value column A)</li>
  <li>number 3, 5 to 5</li>
  <li>number 4, 6 to 7</li>
  </ul>
  <p>like this :</p>
  <p>+---------+---------+---------+</p>
  <p>| A | B | C |</p>
  <p>|    1    |    1    |     3   |</p>
  <p>|    2    |    4    |     4   |</p>
  <p>|    3    |    5    |     5   |</p>
  <p>|    4    |    6    |     7   |</p>
  <p>... so on</p>
  <p>How to work out this? Thanks in advanced</p>