My desktop has several user-accounts. Besides the default ones (Administrator, All Users, Default User and Guest) I also have All Users.WINDOWS and Default User.WINDOWS. Furthermore I have Jan Bonte (=my name), Jan Bonte.BBBLAPTOP (BBBLAPTOP is the name of my laptop. I cannot remember creating this user account) and
Jan Bonte.BONTE-01D1E914E which is my current account. I did not make this account myself; I could not think of such a complicated ID. Does anyone know if WINDOWS under specific circumstances ceates user accounts?
More about :automatically created windows user account
Certain programs will create accounts, but they are usually pretty easy to see what they are. Like after installing microsoft's enterprise manager for SQL I now have an account called SQLDebugger with a nice description to go with it. Also, these accounts are restricted to which directories they can access.
If these are all administrator accounts, I think I'd start disabling them and see if it effects any of your programs. Also, run a full virus scan and if you have a malware scanner, run it too.