title: Delete duplicate relationships between two nodes with Cypher where multiple relationships exist between two nodes
body: <p>I would like to delete duplicate relationships between two nodes with Cypher where multiple relationships exist between the nodes. 
  As an example, given:</p>
  
  <pre><code>a-&gt;r1-&gt;b
  a-&gt;r2-&gt;b
  a-&gt;r2-&gt;b
  a-&gt;r3-&gt;b
  </code></pre>
  
  <p>I expect:</p>
  
  <pre><code>a-&gt;r1-&gt;b
  a-&gt;r2-&gt;b
  a-&gt;r3-&gt;b
  </code></pre>
  
  <p>I already looked into the similar <a href="https://stackoverflow.com/questions/18202197/how-do-i-delete-duplicate-relationships-between-two-nodes-with-cypher">questions</a> but they assume all the relationships between two nodes are the same so you can simply keep one and delete the rest, which doesn't work in my case.</p>