title: C# to search duplicates in two strings and write unique value to variable
body: <p>Text 1 : 
  %start : this is start : %End 
  %start : this is different : %End
  %start : this is start 2: %End 
  .
  ;
  ;
  n</p>
  
  <p>Text 2 :
  %start : this is start 3: %End 
  %start : this is start : %End
  %start : this is different : %End
  .
  ;
  ;
  n </p>
  
  <p>Result Should be :
  %start : this is start : %End 
  %start : this is different : %End
  %start : this is start 2: %End 
  %start : this is start 3: %End </p>
  
  <p>Compare Text 1 and Text 2 , Provide unique values in result. Data in both text always lies between tags %start and %End. </p>