Comment 3 for bug 140505

The second form (user setup page) is necessary as you need a default user for the system. This user gets added to the admin group and can sudo.
If you were to type the same name or username as one of the ones you're importing documents and settings from, it would autofill the rest of the form and just reuse those credentials for the default user.

I agree that the interaction between the migration and user setup page is overly complicated and I am open to further suggestions on how to make it more intuitive.