I'm running in the Japan locale, using a pseudo localized Netbeans.
The message does not come from the pseudo localized jar file.
1. Create Web App using wizard
2. Select the JavaServer Faces checkbox and click Finish
3. Expand Configuration Files then open faces-config.xml
4. In the Source Editor add the following bean declaration twice:
The Ide reports an error message not from bundle file.
Created attachment 42116 [details]
I think this comes from xml editor, where checks are done against the schema.
Reassigning to the xml editor for evaluation.
I didnt see this bug after pasting the managed-bean content twice. Since I am not very familiar with JavaServerFaces,
can you please attach your faces-config.xml?
5. After step 4 choose Validate XML from pop-up menu
The error message appears in Output window not from bundle file:
Duplicate unique value [UserBean] declared for identity constraint of element "faces-config". 
6. Double click err link:
Err message will be highlighted in editor with tooltip
Created attachment 47203 [details]
The code gets an org.xml.sax.SAXParseException. This class is from the J2SE code base. We do
SAXParseException.getLocalizedMessage() and then display the localized message. I looked at SAXParseException source
code and they do not localize the exception message. Since the exception msg is from jdk, there isnt much we can do here.