Record would be duplicated on Junction table, if create/save instance of Models has Many-To-Many relationship

There are two model class

class Tags{
public $id;
public $name;

public function initialize(){
    $this->setSource('Tags');

    $this->hasManyToMany(
        "id",
        "TaggedQuestions",
        "tag_id",
        "question_id",
        "Questions",
        "id"
    );
}}

class Questions {
public $id;
public $title;
public $description;

public function initialize(){
    $this->setSource('Questions');

    $this->hasManyToMany(
        "id",
        "TaggedQuestions",
        "question_id",
        "tag_id",
        "Tags",
        "id"
    );
}
}

After question->create(), records would be duplicated on junction table as listed below

id tag_id question_id

79 73 25

80 74 25

81 75 25

82 73 25

83 74 25

84 75 25