Default Landing Pages (Unsubscription) won't allow you to update any other Schema except Profiles Schema.
You will notice that the Access & loading Section doesn't allow selection of any other Schema, it has Profiles schema selected by itself and this filed is greyed out:
Same would hold true if you will duplicate any of these default pages.
Unless you do some custom implementation on your side which could update some other Schema.
But that again would be similar to an alternative mentioned in ACS - Unsubscription Service wherein a Workflow was suggested to monitor the Profiles Schema and then update the custom Schema accordingly.