I've a loop:
{% for addimg in post.addimg_set.all %}
    <p> 
    {{ addimg.execution }}<br>
    {{ addimg.width }} cm x {{ addimg.height }} cm<br>
    {{ addimg.year }}
    </p>
{% endfor %}
I want to display some data as long as they are different. If they are equal i want it only to display once like:
{% if addimg.execution == addimg.execution %}
    {{ addimg.execution }}<br>
{% endif %}
forgive me my python/django still young. Any suggestions?
                        
You may find your answer in documentation.
Check this out: https://docs.djangoproject.com/en/1.8/ref/templates/builtins/#ifchanged