Blog posts with multiple tags are displaying twice on blog listing page

{% for content in contents|unique %}
 {% if loop.index > 1 %}
 {% for topic in content.topic_list %}
 {% unless topic.name == 'Expert Forum Insider' %}

Could it be that you are looping the topic_list here as well?

Your loop here is outputting the HTML once for each topic a content has. So if a content has 2 topics, it’ll appear twice.