After Benny picks up Kjell's bag at the clinic, he discovers that he took the wrong one. But this is clearly the hero prop carried by Kjell, by the noticeable scuff mark on the front.
When Benny and Kjell pretend to be journalists to gain access to Hermansen's secret files, he doesn't seem to know or recognize them although he has encountered them on several occasions and knows who Olsenbanden's three members are.