If you create a widget animation, delete it, and then later try to recreate it, it gives a duplicate name error.
Steps to repro:
Create a new widget blueprint.
Add an empty animation, called “New Anim”
Select this animation and delete it.
Add a new animation and try to give it the same name, “New Anim” it will give you an error saying the animation already exists.
Even if you save and compile you will still get this error. It requires a full shutdown of UE and a restart before you can reuse the old name.