Is it possible for multiple users to share the same username?

I'm currently working on some Sysadmin tasks using a Windows VM provided by my course. Interestingly, I've discovered around five accounts with the same username and hostname, yet each has a unique SID.

I didn't think this was possible. Could this actually occur in real life, or is it simply a strange glitch in the simulated environment I'm using?

I figured that having multiple accounts with identical usernames might lead to problems, such as logging in or configuring a home directory.

I haven't found any explanations online, so I would greatly appreciate any insights you can offer!