How to zip a folder in google drive without having repeated files in it

Using google appscript we can zip a google drive folder. But one problem arises. In google drive you can keep repeating named (same named) files in single folder. But zip file can't do it. So gives a fatal error without even giving a hint. By using this code you can get rid of repeated files and zip folder.

function zipfolder(e) {
  var foldername = e.parameter.emailAddressbx;
      try{
      var folder = DocsList.getFolder("CV/"+foldername);
        }
  catch (e) {
    Browser.msgBox(e);
    Browser.msgBox("Given folder doesn't exist!");
    }
  var cvlist=[];
  var j=0;
  var found = false;

  for(i=0;i    for(k=0;k    if(folder.getFiles()[i].getName() == cvlist[k].getName())
    { found = true;
    break;}
      }
    if (found == false){
   cvlist.push(folder.getFiles()[i].getBlob());
      j++;
    }
    found = false;  
  }
  if(cvlist.length>0){
  var zip = Utilities.zip(cvlist, 'For_download.zip');
  folder.createFile(zip);
  }
}