Duplicating will otherwise keep the same bake directory, which causes a path conflict and requires manual fixing by users. Clearing the path on copy makes it so the default path is generated on baking. This does not change the path when doing internal copies, like - Depsgraph "evaluated" object vs "original" - Appending or linking objects - Making a linked object local Pull Request: https://projects.blender.org/blender/blender/pulls/109014