diff --git a/src/Umbraco.Core/Models/UserExtensions.cs b/src/Umbraco.Core/Models/UserExtensions.cs
index 26f2f89241..0621c83a72 100644
--- a/src/Umbraco.Core/Models/UserExtensions.cs
+++ b/src/Umbraco.Core/Models/UserExtensions.cs
@@ -16,6 +16,8 @@ namespace Umbraco.Core.Models
         /// <returns></returns>      
         public static CultureInfo GetUserCulture(this IUser user, ILocalizedTextService textService)
         {
+            if (user == null) throw new ArgumentNullException("user");
+            if (textService == null) throw new ArgumentNullException("textService");
             return GetUserCulture(user.Language, textService);
         }
 
diff --git a/src/Umbraco.Core/Services/LocalizedTextService.cs b/src/Umbraco.Core/Services/LocalizedTextService.cs
index fceb8951d9..22d57928f9 100644
--- a/src/Umbraco.Core/Services/LocalizedTextService.cs
+++ b/src/Umbraco.Core/Services/LocalizedTextService.cs
@@ -134,7 +134,12 @@ namespace Umbraco.Core.Services
                     var keys = area.XPathSelectElements("./key");
                     foreach (var key in keys)
                     {
-                        result.Add(string.Format("{0}/{1}", (string) area.Attribute("alias"), (string) key.Attribute("alias")), key.Value);
+                        var dictionaryKey = string.Format("{0}/{1}", (string) area.Attribute("alias"), (string) key.Attribute("alias"));
+                        //there could be duplicates if the language file isn't formatted nicely - which is probably the case for quite a few lang files
+                        if (result.ContainsKey(dictionaryKey) == false)
+                        {
+                            result.Add(dictionaryKey, key.Value);
+                        }
                     }
                 }
             }
@@ -150,7 +155,12 @@ namespace Umbraco.Core.Services
                 {
                     foreach (var key in area.Value)
                     {
-                        result.Add(string.Format("{0}/{1}", area.Key, key.Key), key.Value);
+                        var dictionaryKey = string.Format("{0}/{1}", area.Key, key.Key);
+                        //i don't think it's possible to have duplicates because we're dealing with a dictionary in the first place, but we'll double check here just in case.
+                        if (result.ContainsKey(dictionaryKey) == false)
+                        {
+                            result.Add(dictionaryKey, key.Value);
+                        }
                     }
                 }
             }
diff --git a/src/Umbraco.Tests/Services/LocalizedTextServiceTests.cs b/src/Umbraco.Tests/Services/LocalizedTextServiceTests.cs
index ba1ad70b8c..97ed516846 100644
--- a/src/Umbraco.Tests/Services/LocalizedTextServiceTests.cs
+++ b/src/Umbraco.Tests/Services/LocalizedTextServiceTests.cs
@@ -89,6 +89,28 @@ namespace Umbraco.Tests.Services
         }
 
 
+        [Test]
+        public void Using_XDocument_Gets_All_Stored_Values_With_Duplicates()
+        {
+            var culture = CultureInfo.GetCultureInfo("en-US");
+            var txtService = new LocalizedTextService(
+                  new Dictionary<CultureInfo, Lazy<XDocument>>
+                {
+                    {
+                        culture, new Lazy<XDocument>(() => new XDocument(
+                            new XElement("language",
+                                new XElement("area", new XAttribute("alias", "testArea1"),
+                                    new XElement("key", new XAttribute("alias", "testKey1"), "testValue1"),
+                                    new XElement("key", new XAttribute("alias", "testKey1"), "testValue1")))))
+                    }
+                });
+
+            var result = txtService.GetAllStoredValues(culture);
+
+            Assert.AreEqual(1, result.Count());
+
+        }
+
         [Test]
         public void Using_Dictionary_Returns_Text_With_Area()
         {