Users create an account and their profile (domain.com/userName) is a template pulling info from craft users.
Each user can create entries, all stored in a Structure section (domain.com/userName/entrySlug).
Problem is when different users have an entry with the same title, entrySlug can become entrySlug-1 etc. Although the URL is unique, the slug obviously can't be with entries in the same structure.
But I cannot think how to set this up. A structure per user seems overkill.