Duplicate Account; may fail if no longer licensed for Account Type Promotions

When duplicating an Account, clicking Next on the "Account Type" page may fail with a "You are not licensed for the 'Promotions' Add-On." error.

Steps to recreate:

1. Database is licenced for "Promotions".
2. An Account is added with a Promotion.
3. Database licence for "Promotions" is removed.
4. The Account from step 2, i.e. one with a promotion, is duplicated.