Copy multilingual doc should not copy reference to translated doc

Upon copying multilingual document in Hippo CMS, the references to the translations are copied as well. This should not be the case.

Reproduction:
example english document: "boat" which has a Dutch translation "boot".
Copy document "boat" in Hippo CMS to "train". Now "train" has a Dutch translation: "boot". This should not be the case. "train" should have no translations.