Listing shortcode for 2 categories

Please be so kind and let me know, how can I list events from 2 specific categories?

I mean, the list have to show the events, which have both of the specific categories.

I tried this:
[ecs-list-events cat=’category-1, category-2′ thumb=’true’]
but in this case the list shows all of the events, which received the category-01 OR category-02.

Thank you very much.

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