Pluck from belongsTo relation

I have three Models named as Lead, Address, State. They are related with one to one relation. like below. On Lead Model:

//On Lead Model:
public function address () {
	return $this->belongsTo(Address::clsss, 'account_id');
}

//On Address Model:
public function state() {
	return $this->belongsTo(State::clsss, 'state_id');
}

//My Query
$models = Lead::with('address.state')->get();

//sample output:
Array
(
    [0] => Array
        (
            [account_id] => 71526
            [lead_address] => Array
                (
                    [account_id] => 75465
                    [state_id] => 2
                    [state] => Array (
                        [state_id] => 2
                        [state_name] => 'WB'
                    )
                )

    )
)

If I map this output like below I get all models from State in state_name key.

 $models = $models->map(function ($model)  {
                $address = $model->address;
                $model->state_name = $address->state->pluck('state_name');
                return $model;
 });

But If I append value in State model with $append property I see n number of duplicate quaries. What am I missing?