How can I put two different textures on the front and back of a plane?

PRoblem: i'm trying to create (just for fun) a simple poker card (with a card back and a card front). I have two different images, for back and front. I easily created a Plane geometry with a single texture for both sides, but i really don't know how to assign a texture for a side and the other texture for the other side... i tried this (without success :( ):

var textureBack = new THREE.ImageUtils.loadTexture( 'images/cardBack.png' );
var textureFront = new THREE.ImageUtils.loadTexture( 'images/cardFront.png' );      

var material1 = new THREE.MeshBasicMaterial( { map: textureBack } );
var material2 = new THREE.MeshBasicMaterial( { map: textureFront } );

var geometry = new THREE.PlaneGeometry( 90, 110, 1, 1 );            
geometry.faces[ 0 ].materials.push( material1 );
geometry.faces[ 1 ].materials.push( material2 );

var card = new THREE.Mesh( geometry, new THREE.MeshFaceMaterial());

any help, please? :)