I see the same users both in members and visitors section

I see the same users both in members and visitors section. Is it normal for KanBo?

Yes, it is normal since KanBo chooses the highest levels of permission.When user is in both members and visitors sections, member status is being automatically choosen by KanBo and visitor status is being ignored.

This is sometimes a consequence of changing user permissions in the SharePoint site. If this issue is still a problem, you can set manually permissions by changing status of users to owners, members or visitors in SharePoint site.