This appears to be related to the way in which you have it set up. It would simplify the breadcrumbs if you only have 1 forum, and the system is laying it out on the front end as if you do, which is what is giving you the listing plus subforums.
Thank you for bringing this issue to our attention! I can confirm this should be further reviewed and I have logged an internal bug report for our development team to investigate and address as necessary, in a future maintenance release.