Bug : duplicate objects during import with relations between objects

Seems that the import restrictions ' ... on idno ... ' do not work correctly at least in an xlxs mapping

I've made several tests, without solving my problem of multiples couples of objects with the same idno, sometime with preferred_labels = idno (exact match uppercase), sometimes with preferred_labels = ???, (with my original mapping and datafile, i've imported quite the double of objects !)

Simple example:
I join my excel test data file, my excel mapping file, very short and made for the tests using default.xml profile (no change).

Have a look at the Search object UI using * as wildcard : the sequentialy created objects are :

Object identifier Name (be careful of lowercase and UPPERCASE)
OBJECT_1 Object 1
OBJECT_2 OBJECT_2
OBJECT_3 OBJECT_3
OBJECT_2 Object 2
OBJECT_3 Object 3

due to the data file : (Object 1, object1) is created, ok

due to the refinery objectSplitter {"relationshipType": "similar", "objectType": "document", "delimiter": ";"}, (OBJECT_3, OBJECT_3) and (OBJECT_2, OBJECT_2) are created.

due to the data file : (Object 2, object2) is created, nok : should overwrite or merge

due to the refinery objectSplitter {"relationshipType": "similar", "objectType": "document", "delimiter": ";"}, (OBJECT_1, object 1) is linked.

due to the data file : (Object 3, object3) is created, nok : should overwrite or merge

no refenery for OBJECT_3

Analysis :
First refinery is ok, no possible indication of preferred_labels, so idno is selected for 'preferred_labels'
Second refinery is ok, found OBJET_1

But I've choosen one of the three possibilites for existingRecordPolicy

merge_on_idno
merge_on_idno_with_replace
overwrite_on_idno

I can't select an existingRecordPolicy with 'prefered_labels' choices, it is not possible to pass this data to the refinery.

The end of the analysis is :
if the object (idno, preferred_label) exist, merge or overwrite is working on idno
if the object (idno, preferred_label) does not exist, the merge or overwrite does not work on idno.

There is a problem : temporary index ? always match idno and preferred_labels ?