You can add the same IP address under White-list & Blacklist section.
But there are different locations where plugin takes Whitelisted & Blacklisted IPs into consideration. It will never check both at the same time.
You can configure IPs under Whitelist to bypass 2FA & configure IPs under Blacklist to prevent access to the application.
The plugin always considers the Blacklisted IPs first & based on this it will decide whether to show the login page or decline access for the application.
If IP is not Blacklisted only then access to the application is provided. Once the user is successfully authenticated, then only Whitelisted IPs are considered & based on this, the plugin will decide whether to skip 2FA or not