PDF DOWNLOADING from titanium cloud ANDROID/IOS

hello , I'm using the method httpclient download a pdf from titanium cloud . The binary file is saved in applicationDataDirectory with the corresponding name of the cloud ... but when I download such a file 7MB I saw that are saved 14MB in applicationDataDirectory. The file is saved twice? would know someone explain why ? thanks in advance! This is my code:

Cloud.Files.show({
       file_id: evt.id
       }, function (e) {
 
       if (e.success) {
      var file = e.files[0];
 
       if (file.processed === true) {         
              var f = Ti.Filesystem.getFile(Ti.Filesystem.applicationDataDirectory, file.name);
 
            if (!f.exists()) {
                 var isDownloading = false;
                 var percent_done = 0;
 
                 var xhr = Titanium.Network.createHTTPClient({                          
                    onload: function() {
                        Ti.API.info('isDownloading = ' + isDownloading);
 
                        if (isDownloading === false) {
                            dialog('download interrotto');
                        } else{
                           if (this.responseData !== null) {
                            if (f.write(this.responseData) === false) {
                        dialog('Salvataggio FILE non riusciuto, ritenta il download...');
                        isDownloading = false;
                        f = null;                                                               
                         } else{
                          Ti.API.info('PDF salvato in: ' + f.resolve());
                          ind.message = "Download complete";
 
                        if (isAndroid) {                                            
                            launch(copyToTemp(f, file.name));                                   
                        } else{
                        var docViewer = Ti.UI.iOS.createDocumentViewer({url: f.resolve()});
                            docViewer.show();
                        }
                            isDownloading = false;
                        f = null;                                   
                        };                          
                            } else{
                                dialog('Download del FILE non riuscito, riprova più tardi...');
                             }          
                            }                                                                   
                },                              
            onerror: function () {
                    dialog('onerror: FILE download non riusciuto, riprova più tardi...');
                    activityIndicator.hide();
                    f = null;
                    },
            ondatastream: function (arg) {
                     activityIndicator.hide();
                     ind.show();
                     ind.value = arg.progress;
 
                    var curr_percent_done = parseInt(arg.progress*100);
                     if (percent_done == curr_percent_done) return;
                        percent_done = curr_percent_done;
                        console.log(percent_done+"% done. readyState: "+this.readyState);
                      },
            onreadystatechange: function () {
                    Ti.API.info('READYSTATE: ' + this.readyState);
 
                    if (this.readyState <= 3) {
                        isDownloading = true;
                        Ti.API.info('isDownloading = ' + isDownloading);
                        }                           
                    },  
            timeout: 60000
            });
            xhr.open('GET', file.url);
            xhr.send();
 
            win.addEventListener('close', function() {
                if (isAndroid) {
                var tempDir = Ti.Filesystem.getFile(Ti.Filesystem.tempDirectory, 'tempDir');
                if(tempDir.exists()) { tempDir.deleteDirectory(true); }                 
                };                  
                if (isDownloading === true) {
                    isDownloading = false;
                    xhr.abort();
                    f = null;
                }                       
            });
 
             }

function copyToTemp (srcFile, fileName) {
 
    var tempDir = Ti.Filesystem.getFile(Ti.Filesystem.tempDirectory, 'tempDir');
    if(!tempDir.exists()) { tempDir.createDirectory(); }
 
    var tempFile = Ti.Filesystem.getFile(tempDir.resolve(), fileName); 
    tempFile.write(srcFile.read());
 
    return tempFile;
}
 
// launch intent to read pdf
function launch (file) {
  Ti.API.info(" ---------> launching pdf path: " + file.getNativePath());
  var intent = Ti.Android.createIntent({
    action: Ti.Android.ACTION_VIEW,
    data: file.getNativePath(),
    type: "application/pdf"
  });
  Ti.Android.currentActivity.startActivity(intent);
}