var banner = new Array();

banner[0]='https://i299.photobucket.com/albums/mm308/AntonioAJV23/logo01.jpg';
banner[1]='https://i299.photobucket.com/albums/mm308/AntonioAJV23/logo02.jpg';

document.getElementById('logo').firstChild.src= banner[Math.floor(Math.random()*banner.length)];