Your preferred nickname doesn't necessarily need to be tied to your account name, on a great many/most networks. Indeed, you can usually change nicknames without losing your 'Logged In' state. Some networks might log you out.
If you changed nicknames, your Main Nickname or Alternate Nickname might have changed within mIRC's settings (depending on preferences).
In most cases, people do choose their primary nickname as their account name.
Usually, the matching nickname cannot be 'ungrouped' or detached from an account without first renaming or dropping the account.
You can usually group multiple nicknames to an account, and this often allows you to utilize those alternate nicknames as substitution for your account name, for use as your login credentials. In KindOne's case, grouping KindTwo to his account would let him log in. Otherwise, he'd have to explicitly specify KindOne in his login credentials while sitting on the nickname KindTwo.
You can often log into your account while using any unregistered nickname, assuming you provide both account name and password in the login attempt, since your account name can't be implied from any unregistered and ungrouped nickname.
People often use scripts to log in under a randomized alternate nickname so they don't have to wait for their ghost(s) to die. Once logged in under their account (while using a random nickname), they can ghost kill (regain) their primary nickname.
All these cases I mentioned are accurate with Freenode and/or other networks I also frequent.
Now let's talk about ZNC, and other bouncers. Your Account name is usually both a combination of your proxy ownership credentials, and the IRC network you wish to be connected to. This is because ZNC reuse the same IP:PORT combination. Raccoon/freenode as my Account name would tell ZNC that I want to connect to freenode instead of EFnet.
On this note, I recall mIRC having an issue creating two server entries with the same IP or DNS name. I believe some tricks to get around this were manually creating duplicate entries in the servers.ini file via notepad, or alternating the CaSe.oF.tHe.dNs.NaMe, or choosing an alternate subdomain from their list of vanity hosts, and other similar string hacks to get around mIRC denying duplicate server entries. I'm not sure whether these tricks are still necessary today, but they shouldn't need to be.