With this, you proxy to two methods you don't actually need to call. `attach()` meant for single listeners, not aggregated listeners. An aggregate is [proxied to `attachAggregate()`](https://github.com/zendframework/zf2/blob/master/library/Zend/EventManager/EventManager.php#L278-L280). The aggregate attachment method is then [proxied to `attach()`](https://github.com/zendframework/zf2/blob/master/library/Zend/EventManager/EventManager.php#L323-L326) on the aggregate itself.

If you revert this change, it will save you two calls :)