I'm using WPML because back then when I made the site qTranslate-XT was not working properly.
But suddenly I experience a new problem:
In the English version I see both languages displayed, meaning 8 events although there are only 4 in the chosen category. You can see it here: http://practice.de/events/
In the German version the problem does not appear: http://practice.de/de/events
I've already spoke to the WPML support but after they looked into it, they said I should speak to the theme developers:
"Dies passiert auch, wenn WPML deaktiviert ist und die Kategorien autonom bzw. getrennt angelegt werden. Wenden Sie sich somit am besten an den Theme-Autor, damit dieser den Loop er Taxonomies überprüfen kann."
Thank you for your help!
BEN