URL Variables with/w/o slashes Upload Directories vs Resource URLs
Its not a bug, adding extra '/' won't make any difference. The variables shown Directories and Resource URL forms have same naming conventions however they are rendered in different way for each form. 

CiviCRM Resource URL: [civicrm.root]/

Image Upload URL: [civicrm.files]/persist/contribute/


Your Settings looks fine.

Cheers

Pradeep