Same documents can be upload twice through "Add Multiple Documents"

• Type: Regression Bug
• Status: Closed
• Resolution: Won't Fix
• Affects Version/s: 6.2.0 CE RC4
• Fix Version/s: 6.2.0 CE RC4
• Component/s: DM
• Labels: None
• Environment: Tomcat 7.0 + MySQL 5. Portal master GIT ID: 5ed5f06618bc59669bd36269417b8b47e7cd7e84.
• Story Points: 3
• Fix Priority: 3

Steps for reproduce:

1. Add Documents and Media portlet to the page.
2. Add Multiple Documents.
3. Upload two files and save.
4. Add Multiple Documents again.
5. Upload the previous two files and save again.
6. Check the name of the two files.

Actual result:
The same files can be upload twice and have an exception name.

Expected result:
The same files can not be upload twice with a message:

The folder you selected already has an entry with this name. Please select a different folder.