Hi @Greg Bonk ,
This value is generated by Active Directory automatically if the SamAccountName is not specified on creation. For example, if you used a PowerShell script to create the users, Active Directory generates the SamAccountName.
You can change it to any unique value you need. To avoid such situations, you can specify the required value upon creation. Note that Active Directory does not allow you to have more than one user with the same full name within a domain.
If the information helped you, please Accept the answer. This will help us as well as others in the community who may be researching similar questions. Otherwise let me know if you have further questions.