diff -Nuar ubiquity.old/ubiquity/install_misc.py ubiquity/ubiquity/install_misc.py
--- ubiquity.old/ubiquity/install_misc.py	2013-02-18 11:50:49.026884728 +0100
+++ ubiquity/ubiquity/install_misc.py	2013-02-18 13:07:03.261567131 +0100
@@ -1090,6 +1090,18 @@
         langpacks_file = '/var/lib/ubiquity/langpacks'
         if os.path.exists(langpacks_file):
             osextras.unlink_force(langpacks_file)
+        p1 = subprocess.Popen(['dpkg','-l'],stdout=subprocess.PIPE).communicate()[0]
+        p1 = p1.decode('utf-8')
+        list_packages = p1.split('\n')
+        installed_language_pack = []
+        for package in list_packages:
+            try:
+                package_name = package.split(' ')[2]
+                if package_name.startswith('language-pack-'):
+                    installed_language_pack.append(package_name)
+            except:
+                pass
+
         if install_new:
             if save:
                 if not os.path.exists(os.path.dirname(langpacks_file)):
@@ -1096,7 +1108,8 @@
                     os.makedirs(os.path.dirname(langpacks_file))
                 with open(langpacks_file, 'w') as langpacks:
                     for pkg in to_install:
-                        print(pkg, file=langpacks)
+                        if pkg not in installed_language_pack:
+                            print(pkg, file=langpacks)
                 return []
             else:
                 return to_install