This is kind of an edge case bug report.
The issue occurs when mixing between at least 3 animations.
1: First animation is set, this animation has an event on a specific frame
2: Second animation is added with a mix duration such that it is fully mixed in on that particular frame
3: Third animation is set during the timeframe where the second animation is mixing in.
When the second animation is fully mixed in, it is time for the first animation to trigger the event. This happens, and keeps happening every frame, until the third animation is fully mixed in.
I have created a test case here:
https://github.com/smaren/spine-runtimes/blob/spine-event-bug/spine-ts/webgl/demos/eventbug.js
