title: Primary key + Composite primary key causing issue in propel database schema
body: <p>I have a table that uses an auto-incremented primary key and it has several fields. </p>
  
  <pre><code>&lt;column name="id" type="INTEGER" primaryKey="true" required="true" autoIncrement="true" /&gt;
  &lt;column name="field1" type="INTEGER" required="true" /&gt;
  &lt;column name="field2" type="INTEGER" required="true" /&gt;
  &lt;column name="field3" type="INTEGER" /&gt;
  &lt;column name="field4" type="INTEGER" /&gt;
  &lt;column name="field5" type="INTEGER" /&gt;
  </code></pre>
  
  <p>I want to make sure that a <code>field1</code> + <code>field2</code> combo isn't used more than once, so I added them as primary keys in addition to the id, but this is creating problems when I try to use <code>findPK()</code>. I would prefer to have an auto-incremented id as primary key but I also want to make sure that the combo <code>field1</code> + <code>field2</code> isn't entered more than once. </p>
  
  <pre><code>&lt;column name="id" type="INTEGER" primaryKey="true" required="true" autoIncrement="true" /&gt;
  &lt;column name="field1" type="INTEGER" required="true" primaryKey="true" /&gt;
  &lt;column name="field2" type="INTEGER" required="true" primaryKey="true" /&gt;
  </code></pre>