-Fixed JTokenWriter error with duplicate properties

Src/Newtonsoft.Json.Tests/Linq/JTokenWriterTest.cs

@@ -265,6 +265,28 @@ namespace Newtonsoft.Json.Tests.Linq
 ]", writer.Token.ToString());
         }
 
+        [Test]
+        public void WriteDuplicatePropertyName()
+        {
+            JTokenWriter writer = new JTokenWriter();
+
+            writer.WriteStartObject();
+
+            writer.WritePropertyName("prop1");
+            writer.WriteStartObject();
+            writer.WriteEndObject();
+
+            writer.WritePropertyName("prop1");
+            writer.WriteStartArray();
+            writer.WriteEndArray();
+
+            writer.WriteEndObject();
+
+            StringAssert.AreEqual(@"{
+  ""prop1"": []
+}", writer.Token.ToString());
+        }
+
         [Test]
         public void DateTimeZoneHandling()
         {

Src/Newtonsoft.Json.Tests/Serialization/JsonSerializerTest.cs

@@ -8630,11 +8630,11 @@ Path '', line 1, position 1.");
         [Test]
         public void DuplicatePropertiesInNestedObject()
         {
-            ExceptionAssert.Throws<ArgumentException>(() =>
-            {
-                string content = @"{""result"":{""time"":1408188592,""time"":1408188593},""error"":null,""id"":""1""}";
-                JsonConvert.DeserializeObject<JObject>(content);
-            }, "Can not add property time to Newtonsoft.Json.Linq.JObject. Property with the same name already exists on object.");
+            string content = @"{""result"":{""time"":1408188592,""time"":1408188593},""error"":null,""id"":""1""}";
+            JObject o = JsonConvert.DeserializeObject<JObject>(content);
+            int time = (int)o["result"]["time"];
+
+            Assert.AreEqual(1408188593, time);
         }
 
         [Test]

Src/Newtonsoft.Json/Linq/JTokenWriter.cs

@@ -166,9 +166,17 @@ namespace Newtonsoft.Json.Linq
         /// <param name="name">The name of the property.</param>
         public override void WritePropertyName(string name)
         {
+            JObject o = _parent as JObject;
+            if (o != null)
+            {
+                // avoid duplicate property name exception
+                // last property name wins
+                o.Remove(name);
+            }
+
             AddParent(new JProperty(name));
 
-            // don't set state until after in case of an error such as duplicate property names
+            // don't set state until after in case of an error
             // incorrect state will cause issues if writer is disposed when closing open properties
             base.WritePropertyName(name);
         }

Src/NuGet.Config

@@ -3,7 +3,6 @@
   <packageSources>
     <!--To inherit the global NuGet package sources remove the <clear/> line below -->
     <clear />
-    <add key="api.nuget.org" value="https://api.nuget.org/v3/index.json" />
-    <add key="nuget.org/api/v2" value="https://nuget.org/api/v2/" />
+    <add key="api.nuget.org" value="https://api.nuget.org/v3/index.json" protocolVersion="3" />
   </packageSources>
 </configuration>