When Local Adjustments are copied all LAs in the target image actually are being replaced. All. That should always be optional (ADD; REPLACE) except when in the exact position there is already a LA. In this case user should be informed that not all could have been copied.
I was adressing this to DXO-Support (Barbara, german support) and she wrote she’s gonna adress it (hopefully) to the development-team.
A LIKE here could possibly increase the priority.