We are using LoginWithCustomID and seeing inconsistent behavior. The docs say CustomId is unique, but it's unclear whether that uniqueness is enforced on the server. Our initial thoughts were that the uniqueness is enforced but then we ended up with two accounts with the same CustomId of "GettingStartedGuide" (from using the identical code from the Unity Getting Started Guide).
The first time we logged in with that CustomId, it created the account. The next few logins it just logged the user in and didn't create new accounts. Later, however, it created a new account with the exact same CustomId. When does the system know if it's the same user logging in vs a new user? Is uniqueness guaranteed on the server?
Obviously we wouldn't use simple things such as "GettingStartedGuide" as our ID.