This massive, free rigging toolset actually includes a "Copy/Paste" engine that handles layer duplication better than the native AE tool.
If you can’t find a legal free version of the specific "True Layer Duplicator," these alternatives offer similar functionality for $0: true layer duplicator free download
The script is available as a "name-your-price" tool, meaning you can download it for free by entering $0 or support the creator with a donation. This massive, free rigging toolset actually includes a