Why is the Activity instantiated twice?

I'm implementing facebook's sdk to sign in to my app. I have two Activities that I call Login and Home. When I click the login button, login is done perfectly and Activity Home is instantiated as soon as the onSessionStateChange method is called:

private void onSessionStateChange(Session session, SessionState state,
        Exception exception) {
    if (state.isOpened()) {
        Intent intent = new Intent(getActivity().getBaseContext(), HomeActivity.class);
        startActivity(intent);
        getActivity().finish();
    } else if (state.isClosed()) {
        Log.i(TAG, "Logged out...");
    }

}

The problem is that the instance code is twice the activity activity.