Created attachment 355102 [details]
Screenshot

If you click on them, you can see that they have an ID tag which identifies them as "langpack-as.org" and "langpack-or.org".  I suspect that these are other languages, apparently Assamese and Oriya (see ISO 639), whose creators didn't put in a name string in the right way, and so Firefox called them "English (US)" by default.

Actually, it's just that the contributors didn't change the name string from whatever they used for a template.

/usr/lib/firefox-3.5.1/extensions/langpack-as.org/install.rdf

<RDF xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
     xmlns:em="http://www.mozilla.org/2004/em-rdf#">
  <Description about="urn:mozilla:install-manifest"
               em:id="langpack-as.org"
               em:name="English (US) Language Pack"
               em:version="3.5.1"
               em:type="8"
               em:creator="mozilla.org">
    <em:contributor>Amitakhya Phukan &lt;aphukan&gt;</em:contributor>
....


/usr/lib/firefox-3.5.1/extensions/langpack-or.org/install.rdf

<RDF xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
     xmlns:em="http://www.mozilla.org/2004/em-rdf#">
  <Description about="urn:mozilla:install-manifest"
               em:id="langpack-or.org"
               em:name="English (US) Language Pack"
               em:version="3.5.1"
               em:type="8"
               em:creator="mozilla.org">
....

Definitely needs an upstream fix.  Could be patched meanwhile.

We filed this bug in the upstream database (https://bugzilla.mozilla.org/show_bug.cgi?id=508130) and believe that it is more appropriate to let it be resolved upstream.

We will continue to track the issue in the centralized upstream bug tracker, and will review any bug fixes that become available for consideration in future updates.

Thank you for the bug report.