symfony - Twig template parent() caused double parent block -

i have base.html.twig template.html.twig , dashboard.html.twig. dashboard extends template extends base.

base:

{% block javascripts %}      <script src="1.js"></script>  {% endblock %} 

template:

{% block javascripts %}      {{ parent() }}     <script src="2.js"></script> {% endblock %} 

dashboard:

{% block javascripts %}     {{ parent() }}     <script src="3.js"></script> {% endblock %} 

this templating setup resulted in redundant script tags doubled this

<script src="1.js"></script> <script src="2.js"></script> <script src="3.js"></script> <script src="1.js"></script> <script src="2.js"></script> <script src="3.js"></script> 

am missing something? why happening?

edit1:

base.html.twig:

extends nothing 

template.html.twig:

{% extends 'base.html.twig' %} 

default/dashboard.html.twig:

{% extends '::template.html.twig' %} 

in opinion {% extends "file" %} bad.

the fix :

template :

{% extends "base_path" %} {% block javascripts %}      {{ parent() }}     <script src="2.js"></script> {% endblock %} 

dashboard :

{% extends "template_path" %} {% block javascripts %}     {{ parent() }}     <script src="3.js"></script> {% endblock %}