Accounts setUsername fail with user alaready exists

This Meteor 1.4 server code uses
[email protected]
[email protected]

is giving the following error:

Exception in callback of async function: Error: Useame already exists. [403]

console.log(oldUseame); //=> abc121111
console.log(newUseame); //=> abc123333
Accounts.setUseame(userId, newUseame);

Surly the console.log shows they are different. why is it failing and how to fix it? Thanks