There\'s already an answered question about the same subject but as it\'s from \'09 I consider it outdated.
How to properly implement \"Confirm Password\" in ASP.NET
Take a look at the default VS2010 template for a MVC3 app.
It contains a RegisterModel (a 'ViewModel') that contains the Password and ConfirmPassword properties. The validation is set on the ConfirmPassword.
So the answer is that the Models in MVC don't have to be (usually aren't) the same as your business Models.