I have duplication in title tag


I have duplication in <title></title> at the main page of the questions of Q&A plugin.
At the end of the title should be only one "79" but there is "79|79".
I think that the reason for it is the yoast plugin.
Since that page is an archive page I was look for it in the exonomy tab but couldn't find the spot to change it. I olso tried in the rest of the fileds there.

Do you have any idea how can I fix this?
Here's the link to problematic page:


Thank you