Hyperspace uses built in APFS features, it just applies them to existing files.
You only get CoW on APFS if you copy a file with certain APIs or tools.
If you have a program that does it manually, you copied a duplicate to somewhere on your desk from some other source, or your files already existed on the file system when you converted to APFS because you’ve been carrying them for a long time then you’d have duplicates.
APFS doesn’t look for duplicates at any point. It just keeps track of those that it knows are duplicates because of copy operations.
You only get CoW on APFS if you copy a file with certain APIs or tools.
If you have a program that does it manually, you copied a duplicate to somewhere on your desk from some other source, or your files already existed on the file system when you converted to APFS because you’ve been carrying them for a long time then you’d have duplicates.
APFS doesn’t look for duplicates at any point. It just keeps track of those that it knows are duplicates because of copy operations.