Just ask staff to change it for u then close the other account.
Staff won't ban you for this, because you're not maliciously using 2 accounts, It's just a circumstantial thing.
One of the staff members will see this and will probably PM you about it. Make a report ticket as well to make sure staff understand the situation.
I basically have 2 accounts.
One of them (this account) I created via Facebook, and the other I created 7 years later via email after forgetting about the 1st account. I then logged in via Facebook and rediscovered the 1st account. I then permanently switched back to the 1st account.
I'm pretty sure I didn't play any games with the 2nd account (handle: evilishies) I know the TOS and would never intentionally violate them. Anyway, I want to change my username on this account to this handle. (It's important for my nonexistent Twitch career) But when I try, I get the (obvious) error: "Account Already In Use"
So I'm basically wondering, this is a kind of weird situation. I can log into my 2nd account and change the handle. Does it then become available to this account to claim? How quickly?