Improve error message duplicate folder/document (SNS issue)

The error message is misleading; after fixing the url (by clicking edit), you still have to make the name unique.
You do not get a separate message for the name.

Quick fix: It is better to put URL in brackets in the error message.

Reproduction path:
1) Go to the CMS, Content perspective and select a folder for adding documents
2) Create a document, with name (and URL name) "test".
3) In the same folder, try to create another document with the same name and URL name, and click OK.

Expected behavior: The CMS provides comprehensible feedback that two documents in the same folder cannot have the same name or the same URL name.
Actual Behavior: see screenshot.