mcduff is absolutely right, I just wanted to add a little bit about what registering for events does.
When you work with queues there is a single queue reference which the sender uses to send data, and the receiver uses to receive data. Multiple senders is fine if you don't care about the order the data is received, so we can use queues with N senders and 1 receiver, also called N:1 messaging. You never want to dequeue elements from a queue in multiple places at the same time, because only one of them can get the element.
When you work with events, you get two references. The event reference is used by the sender to send data, and the event registration is used by receiver to receive data. For the same reason you don't want to dequeue from a queue at multiple places, you also don't want to receive events from the same event registration in multiple places. However, if you create multiple event registrations, you will have no problem receiving the event data in multiple places. This could be used for N:N messaging, but usually the event is triggered by a specific module or process in your code, so it tends to be used for 1:N messaging.
If you handle a single event registration in two event structures that have an equal chance at grabbing it, then it will sometimes be handled by both, and sometimes by only 1. If you fire the event N times, it will be handled between N and 2N times total, but not in any repeatable way. In this way, it is a little bit different than dequeueing from a queue in multiple places, because then each element can only be dequeued once.
