Moved database to new server, not sure about NT AUTHORITY\* users

I just moved database to new instance of SQL Server (SQL Server 2012 Web from Amazon EC2) and am now cleaning up database users. I am not sure if/why these 2 users are needed (they exist in original database): - NT AUTHORITY\IUSR - NT AUTHORITY\NETWORK SERVICE Note that there are also 2 database schemas with exactly the same names. I am more clear on NT AUTHORITY\IUSR - this seems to be a user for IIS. IIS is not even installed on the new instance, so this one probably can be deleted. I am not sure about NT AUTHORITY\NETWORK SERVICE (or how it got created to begin with - new databases created on new server don't have it, or NT AUTHORITY\IUSR) Neither of these 2 users exist at server level on a new instance or on an old instance.