Edge document with user provided key is inserted as many times as the number of shards

[theoks]

ArangoDB edition: 3.3.10 Enterprise
ArangoDB go-driver master branch commit c2828ac

I have an edge collection with the following options:

keyOptions := &driver.CollectionKeyOptions{
	AllowUserKeys: true,
}

options := &driver.CreateCollectionOptions{
	ReplicationFactor: 2,
	NumberOfShards:    20,
	Type:              driver.CollectionTypeEdge,
	IndexBuckets:      64,
	KeyOptions:        keyOptions,
}

Then I try with a custom key to add the following document:

LET edge = ( 
	INSERT {
		_key: @key,
		_from: @fromID,
		_to: @toID
	} IN @@edgeCollection 
	RETURN NEW)

RETURN edge

The result is that I have 20 documents added in the collection (equal to the number of shards). If I change the number of shards, the number of the inserted documents still matches the number of shards.

However if I do not use a user provided key the insertion works as expected.

EDIT: I checked the same query through the ArangoDB UI and it seems to work properly, so I presume that this has to do with the driver.

[theoks]

I posted the same issue on the main repo of the database and the engineers could recreate it, so it is not a driver issue. I will post a link whenever there is an actual solution to the problem.