Animation clean up and the Clean up button removes second and subsequent sequence keys

[misaki-eymard]

Description:
If you enable Animation clean up in the export settings or select an animation and use the Clean up button, the second and subsequent sequence keys on the same timeline will be removed.

Expected behavior:
The second and subsequent sequence keys are retained even if Animation clean up is enabled or the Clean up button is used.

Steps to reproduce:
1.Download and unzip the attached zip file:
Animation clean up and the Clean up button removes second and subsequent sequence keys.zip
2.Open the Spine project in it, and make sure there are two sequence keys in the "knock2" animation.

3.Press the Clean up button on the Tree view, and you can see the second sequence key is removed.

The versions of Spine in which this issue were found:
Spine v4.1.17

This bug was reported on this forum post:
http://esotericsoftware.com/forum/unity-don-t-play-correctly-when-reuse-keyframe-sequence-18455

[NathanSweet]

4.1.18