The login dialog appears twice when you log in to facebook android

I am new to development facebook. I want loginto facebookand allow the user to allow my application to publish photos and more. but when the user is loginsuccessful, he twice displays the authorization dialog. Here is my code

Session.openActiveSession(this, true, new Session.StatusCallback() {

            // callback when session changes state
            @Override
            public void call(Session session, SessionState state,
                    Exception exception) {

                if (session.isOpened()) {
                    Log.d("", "usman: session is opened");
                    // make request to the /me API

                    Request.executeMeRequestAsync(session,
                            new Request.GraphUserCallback() {

                                // callback after Graph API response with
                                // user
                                // object
                                @Override
                                public void onCompleted(GraphUser user,
                                        Response response) {
                                    Log.d("", "onCompleted called");
                                    if (user != null) {
                                        // TextView welcome = (TextView)
                                        // findViewById(R.id.welcome);
                                        Log.d(MyConstants.TAG,
                                                "facebook Hello : "
                                                        + user.getName() + "!");

                                        publishStory();
                                        //isShared = true;

                                    } else {
                                        Toast.makeText(
                                                getApplicationContext(),
                                                "Unable to Post,Try Again later",
                                                Toast.LENGTH_LONG).show();
                                    }
                                }
                            });

                } else {
                    Log.d("", "usman: Session is not open");
                }
            }
        });

private void publishStory() {
        Log.d("", "usman: in publishStory");
        Session session = Session.getActiveSession();

        if (session != null) {

            // Check for publish permissions
            List<String> permissions = session.getPermissions();
            if (!isSubsetOf(PERMISSIONS, permissions)) {
                pendingPublishReauthorization = true;
                Session.NewPermissionsRequest newPermissionsRequest = new Session.NewPermissionsRequest(
                        this, PERMISSIONS);
                session.requestNewPublishPermissions(newPermissionsRequest);
                return;
            }

            FileInputStream fis = null;
            try {
                fis = new FileInputStream(fileImage);
            } catch (FileNotFoundException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }
            Bitmap bi = BitmapFactory.decodeStream(fis);
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            bi.compress(Bitmap.CompressFormat.JPEG, 100, baos);
            byte[] data = baos.toByteArray();

            Bundle postParams = new Bundle();

            postParams.putString("name", "London For Less Postcard");
            postParams.putString("caption",
                    "Build great social apps and get more installs.");
            postParams
                    .putString(
                            "description",
                            "The Facebook SDK for Android makes it easier and faster to develop Facebook integrated Android apps.");

            postParams.putByteArray("picture", data);

            Request.Callback callback = new Request.Callback() {
                public void onCompleted(Response response) {
                    JSONObject graphResponse = response.getGraphObject()
                            .getInnerJSONObject();
                    String postId = null;
                    try {
                        postId = graphResponse.getString("id");
                    } catch (JSONException e) {
                        Log.i("FB", "JSON error " + e.getMessage());
                    }
                    FacebookRequestError error = response.getError();
                    if (error != null) {
                        Toast.makeText(
                                SendPostCardActivity.this
                                        .getApplicationContext(),
                                error.getErrorMessage(), Toast.LENGTH_SHORT)
                                .show();
                        Log.d("", "usman: Error");
                    } else {
                        Toast.makeText(
                                SendPostCardActivity.this
                                        .getApplicationContext(),
                                "Posted on facebook wall successfully",
                                Toast.LENGTH_LONG).show();
                        Log.d("", "usman: Finish");
                        finish();
                    }
                }
            };

            Request request = new Request(session, "me/photos", postParams,
                    HttpMethod.POST, callback);

            RequestAsyncTask task = new RequestAsyncTask(request);
            task.execute();
        }

    }