Mouse over picking when polygons switch between batches causes errors

I get the following error message:

Uncaught RuntimeError: An entity with id 26912e0a-e73c-4b55-ac1b-f1bfed18bd22 already exists in this collection.
Error
    at new RuntimeError (http://localhost:8080/Source/Core/RuntimeError.js:43:19)
    at EntityCollection.add (http://localhost:8080/Source/DataSources/EntityCollection.js:283:19)
    at <anonymous>:58:32
    at handleMouseMove (http://localhost:8080/Source/Core/ScreenSpaceEventHandler.js:251:13)
    at HTMLDocument.listener (http://localhost:8080/Source/Core/ScreenSpaceEventHandler.js:68:13) (on line 283 of http://localhost:8080/Source/DataSources/EntityCollection.js)

when I run the following sandcastle examples

var viewer = new Cesium.Viewer('cesiumContainer', {
    selectionIndicator : false,
    infoBox : false
});

var scene = viewer.scene;
var handler;

var pickedEntities = new Cesium.EntityCollection();
var pickColor = Cesium.Color.YELLOW;
function makeProperty(entity, color) {
    var colorProperty = new Cesium.CallbackProperty(function(time, result) {
        if (pickedEntities.contains(entity)) {
            return pickColor.clone(result);
        }
        return color.clone(result);
    }, false);

    entity.polygon.material = new Cesium.ColorMaterialProperty(colorProperty);
}

var red = viewer.entities.add({
    polygon : {
        hierarchy : Cesium.Cartesian3.fromDegreesArray([-70.0, 30.0,
                                                        -60.0, 30.0,
                                                        -60.0, 40.0,
                                                        -70.0, 40.0]),
        height : 0
    }
});
makeProperty(red, Cesium.Color.RED.withAlpha(0.5));

var blue = viewer.entities.add({
    polygon : {
        hierarchy : Cesium.Cartesian3.fromDegreesArray([-75.0, 34.0,
                                                        -63.0, 34.0,
                                                        -63.0, 40.0,
                                                        -75.0, 40.0]),
        height : 0
    }
});
makeProperty(blue, Cesium.Color.BLUE.withAlpha(0.5));

// Move the primitive that the mouse is over to the top.
handler = new Cesium.ScreenSpaceEventHandler(scene.canvas);
handler.setInputAction(function(movement) {
    // get an array of all primitives at the mouse position
    var pickedObjects = scene.drillPick(movement.endPosition);
    if (Cesium.defined(pickedObjects)) {
        //Update the collection of picked entities.
        pickedEntities.removeAll();
        for (var i = 0; i < pickedObjects.length; ++i) {
            var entity = pickedObjects[i].id;
            pickedEntities.add(entity);
        }
    }

}, Cesium.ScreenSpaceEventType.MOUSE_MOVE);

This occurs using Primitives. If you remove the height : 0 from both entities the same thing will occur with GroundPrimitives. It only happens when you force the entity to switch batches during the pick. For Primitive it has to switch between opaque and translucent, for GroundPrimitive it just has to switch color.

[tfili]

@pjcozzi It looks like this is fixed for GroundPrimitives, but is still an issue with regular Primitives (with height:0 in the code).

I suspect that the GroundPrimitives were fixed in 203bdf3c6671a4e6fea6b0fd43b77d62605b497b

[pjcozzi]

@tfili:

The above code worked for me, do you need to remove height : 0 to reproduce this?