Only attribute custom property names are expected to be unique. But also, it isn't worth asserting over this here, so just use the regular "add" method instead of "add_new". Pull Request: https://projects.blender.org/blender/blender/pulls/132277
Only attribute custom property names are expected to be unique. But also, it isn't worth asserting over this here, so just use the regular "add" method instead of "add_new". Pull Request: https://projects.blender.org/blender/blender/pulls/132277