Duplicate username even though it does not exist

[BenWan]

Hi,

I am creating new users on ArcGIS Online, and it is telling me that there are duplicate usernames even though that username does not exist.

Is it because that username may have existed in the past and was deleted, and somehow I cannot create a new username with that same deleted username? Photo below of the error prompt.

[Anonymous User]

I think usernames are AGOL wide, so someone else outside of your org has that name.

[BenWan]

Ah...never thought about that...

It is an online login so it makes sense. I guess I never thought about it since I end all my users with "_rec" and it seemed strange that someone else would have that exact username, but since it is AGOL wide it could happen. Thanks