PostActorCreated Called twice when dragging asset into the level

When dragging an actor from the content browser to the level viewport, PostActorCreated() is called twice, once as the actor enters the viewport while still being dragged and again when the LMB is released and the object is placed in location.

1. Open UE4 Editor (any project)
2. Add code to project based on actor (MyActor)
3. In MyActor.h add the following:

   virtual void PostActorCreated() override;
   

4. In MyActor.cpp add the following:

    void AMyActor::PostActorCreated() {
        Super::PostActorCreated();
        AActor* a = GetWorld()->SpawnActor<AActor>();
        a->SetActorLabel("___TEST");
    }
   

5. Compile the code
6. Create a blueprint based on MyActor and add it to the level

Result:
The world outliner will show two actors named "__TEST"