I was trying to create a user with just email and password using curl, but I forgot to add underbar before User class in the request. It created another User class, created the user in that class and returned the objectId in response.
What's strange is that Parse-dashboard shows this new User class with copies of all the rows and a few columns, but I couldn't find my newly created user there. I tried to delete this User class, but you have to delete all the rows in a class before deleting it. Just to be safe, I started with just one and as I suspected it deleted the user from the default User class as well.
What I think is either it should not be allowed to create a 'without underbar' versions of the default classes or if it is the dashboard shouldn't link the created class with the default class.