No Import of multiple phone numbers for one contact

Sometimes, a contact may have multiple phone numbers of the same category (i.e. "Home") - it is possible to enter this in CiviCRM.

However, the import function is not able to handle this: If you want to import several phone numbers with the same category for one contact, only the last of the rows will "win" - the others don't get imported.

I tried this out in the sandbox for the following contact:
https://sandbox.drupal.civicrm.org/civicrm/contact/view?reset=1&cid=5447

And used the import file attached. (I tried for any combination of dedupe rules as well as for update/fill/no duplicate checking).