[Closed] Post category shows twice with original language (both in NL and EN) somehow.

Background of the issue:
After adding a new post, it automatically is assigned to the Insights category. The latest article shows the Insights category twice. The English version was temporarily renamed to Insights EN. The post is automatically given both the English and NL category. This issue may be caused by the fact that these blog items and the categories were imported before WPML was installed on the new website.

Symptoms:
The Insights category shows twice with original language (both in NL and EN) on the latest article.

Questions:
Could you let me know what the solution may be to get this right?
Should I create completely new categories and reassign everything?