Sticky Multiple Account Info has detected 2 accounts, but I know for sure that both are used by different people. Why are they detected?

It is a common missunderstanding that you can detect singular people with such software. In fact you only can detect singular computers. If the same computer is used by 2 different people with 2 different accounts on your site, both accounts will be detected as "multiple accounts". If you want to remove these 2 accounts from being detected, just add an exemption for them in any of the Multiple Account Info screens (user profile or ACP user edit). This will remove those 2 accounts from being detected as a multiple account when used by the same computer and also notify your staff about the exemption.