It would be a great feature if we could decide to have only unique content names.

At this moment, when we publish some content, eZ Publish automatically checks if a content with the name name/title already exists in the same location, and if it already exists, a numeric value will be appended to the URL alias of that content being created.

Example: If "MyArticle" already exists with URL alias "/MyArticle", a second object with the same name with have URL alias "/MyArticle2".

This is documented here: http://doc.ez.no/eZ-Publish/Technical-manual/4.x/Features/Multi-language-support-for-URL-aliases/URL-transformation-rules

The point here would be avoid appending "2" or "3" to the URL alias if a match already exists, and not publishing it instead.

This can be done by using a before publish workflow to stop the publishing process if a content already exists with the name name/title on the same location.
Additionally we could let the editor that a match already exists and provide the information on the page even before publishing, by using a Javascript based request like Ajax.

Thanks!