this move is highly advised especially for sites with high traffic or are popular because scammers like to imitate this kind of site.
This is my first time to notice that betfury has a mirror site but newbie players will be uncomfortable using it especially those players with huge amount of balance since typically casino has no mirror site like this due to the fact that money is involved while it can be mistake a phishing site especially if you didn't know the list of official mirror site. I never experienced any delays using Betfury so I wonder there's really a lot of player using that mirror site at this moment.
I haven't heard of a single case of phishing with the Betfury site. However, I wouldn't be surprised if scammers have already created a huge number of phishing domains similar to the official ones. So it seems to me that each user should activate 2fa in their account settings as soon as possible. At least this feature may help avoid losing accounts and funds if users fall for phishing attacks on mirror sites.