Nested field collection duplicate items on devel generate

node (location)
- field collection (field_opening_hours) (max limit : 1)
- field collection (field_sunday) (max limit : unlimit)
- text field (field_hours)
- text field (field_hours2)

devel generate on location node for 1 item, result : 1 node is created correctly , but when you look at the field collection database table , there are 2 field_opening_hours items, when you delete the generated node , still have 1 field_opening_hours item left in database.

I think this is because field_collection_field_insert trying to clone a new field_collection causing this issue.