Sequence director fires events multiple times if multiple levels are streaming.

The new event track in level sequences fires the number of times that there are levels streaming.

1. Create a persistent level, and stream in multiple levels (they can be blank).
2. Create a level sequence. Add an event track with one event. Set that event up to print a string when fired.
3. Play that level sequence in the level.

Results: The event is called multiple times, and multiple print strings appear. The number of times the event is called is equal to the number of levels there are streaming.

Expected: The event should fire once, as it's only set up to be called once in the sequence, which is only playing on one level.