To replicate this behaviour is sufficient to fire two event that will be POSTed in the same request to the server; is necessary that these event are bindend to a component that use a model that will be changed by these requests (for example the click operation cause a reload of the model attached to the component that fired the event). In this scenario, when getting the target (getTarget) of the second event, you can see that it's as it's 'detached' from the DOM tree stored in the backend. It's possible that this behaviour is due the fact that the first call change the model, the engine recalculate the id's and attach the new component to the DOM tree (a sort of redraw), then came the second call with an old reference id (reference to the old DOM tree); the engine is capable to retrieve some kind of information about this event's target component but can't reference it to the new DOM tree.