This is a known bug in Spine 4.2 where the Metrics window shows an incorrect number of animations when in Animate mode. Specifically, it adds an extra animation to the count.
The good news is that this issue has been fixed in Spine 4.3! If you upgrade to version 4.3 or later, the Metrics window should display the correct number of animations.
In the meantime, you can verify the actual number of animations by checking the Animations node in your tree view, which will show the correct count.
