If you are trying to add a username that's already in use within the Silvertrac database, you'll receive an error that looks:
That doesn't mean you have created this username before, it just means that another Silvertrac user has that username.
Usernames are how we tie specific users to specific companies so they are tied to our whole database, not just your account.
But don't worry, this is an easy fix. Just try making the username a little more unique. You can do this by adding a few numbers to the end, changing the format, etc.