You've hit upon a special case. Typically, something in a tournament occurs and a notification is generated. The Event code receives notifications and turns them into triggers where appropriate, that then trigger your configured event(s).
When you bust one or more players out of the tournament, many different triggers can result. A player busts out, a player rebuys, a chop is performed, a table balance is suggested. Also, since you can bust out several players at once and rebuy several at once, you can get multiple of those triggers. Furthermore, since this is a chained process (busting players out may lead to buying players in or to a chop, and can then lead to a table balance), these triggers could occur all at once or at various places in the process.
To prevent strange things from happening during this process, the notifications are queued up and not sent until the process ends, at which time they are all delivered at once. Since it would be undesirable (in many cases) to have several events trigger at once, the Events code prioritizes the notifications and allows only one event to be triggered.