How to get unique value of repeated nodes using dom parser

I have a XML having repeated nodes and I have top parse it using DOM parser. After a lot R&D I could find anything on internet which can help me. My xml looks like

<nos1>
  <Name>aqwer</Name>
  <class>sas</class>
  <class>xcd</class>
  <class>asd</class>
  <Name>cfg</Name>
  <Name>cfg</Name>
<nos1>

Any suggestion How can I parse this xml for repeated values.