qualdrop_value causes problems when there are similar fields in input-forms which differ by schema only

We have two similar fields in our input-forms:

dc.contributor.editor
source.contributor.editor

dc.contributor.editor works fine when offered like this

       <field>
         <dc-schema>dc</dc-schema>
         <dc-element>contributor</dc-element>
         <dc-qualifier>editor</dc-qualifier>
         <repeatable>true</repeatable>
         <label>Editor</label>
         <input-type>onebox</input-type>
         <hint></hint>
         <required></required>
       </field>

but not when included in a qualdrop_value

       <field>
         <dc-schema>dc</dc-schema>
         <dc-element>contributor</dc-element>
         <dc-qualifier></dc-qualifier>
         <repeatable>true</repeatable>
         <label>Persons</label>
         <input-type value-pairs-name="roles">qualdrop_value</input-type>
         <hint></hint>
         <required></required>
       </field>

where roles = {author, editor, ...}

When the other field "source.contributor.editor" is present in input-forms, values added for dc.contributor.editor via qualdrop_value are not reflected on the GUI. They are reflected in the database, however entries disappear again when multiple entries are made for dc.contributor.editor (it seems to alternate between insertion and deletion).

When source.contributor.editor is not present in input-forms, adding values for dc.contributor.editor via qualdrop_value works fine. It looks like the schema information is not properly considered by qualdrop_value.