I was working on a project on netbeans and came across a problem with netbeans. The netbeans was showing the error repeatedly as "duplicate class". eventhough there is no duplicate class in the project. After so much frustation , i realized that this is netbeans bug. After doing some search about this , i finally got the solution .
This is the link to get rid of the netbeans duplicate clas bug.
Hope this post will help others who encounter the same problem.