title: How to parse and remove duplicates from aggregated text field
body: <p>I have column with values like</p>
  
  <pre><code>select chipset_name from chipset
  
      chipset_name
      "Chip A,Chip B"
      "Chip A"
      "Chip F"
      "DSOG K"
      "FROW 01 33"
      "Chip F,DSOG K"
      ...
  </code></pre>
  
  <p>I want to aggregate it to one row without duplicate, but if I use string_agg(distinct..) I have duplicates </p>
  
  <pre><code>select string_agg(distinct chipset_labels,',')from chipset
  ----------
  Chip A,Chip B,**Chip A**,Chip F,DSOG K,FROW 01 33,Chip F,**DSOG K**
  </code></pre>
  
  <p>How to parse and remove duplicates?</p>
  
  <p>Thanks</p>