Use scopes to resolve array naming issue.

src/libraries/System.Private.Xml/src/System/Xml/Serialization/XmlSerializationWriterILGen.cs

@@ -1176,6 +1176,7 @@ private void WriteMember(SourceInfo source, AttributeAccessor attribute, TypeDes
                 string aiVar = "ai" + memberTypeDesc.Name;
                 string iVar = "i";
                 string fullTypeName = memberTypeDesc.CSharpName;
+                ilg.EnterScope();
                 WriteArrayLocalDecl(fullTypeName, aVar, source, memberTypeDesc);
                 if (memberTypeDesc.IsNullable)
                 {
@@ -1361,6 +1362,8 @@ private void WriteMember(SourceInfo source, AttributeAccessor attribute, TypeDes
                 {
                     ilg.EndIf();
                 }
+
+                ilg.ExitScope();
             }
             else
             {
@@ -1435,6 +1438,7 @@ private void WriteArray(SourceInfo source, string? choiceSource, ElementAccessor
             if (elements.Length == 0 && text == null) return;
             string arrayTypeName = arrayTypeDesc.CSharpName;
             string aName = "a" + arrayTypeDesc.Name;
+            ilg.EnterScope();
             WriteArrayLocalDecl(arrayTypeName, aName, source, arrayTypeDesc);
             LocalBuilder aLoc = ilg.GetLocal(aName);
             if (arrayTypeDesc.IsNullable)
@@ -1486,6 +1490,8 @@ private void WriteArray(SourceInfo source, string? choiceSource, ElementAccessor
             {
                 ilg.EndIf();
             }
+
+            ilg.ExitScope();
         }
 
         [RequiresUnreferencedCode("calls WriteElements")]

src/libraries/System.Private.Xml/tests/XmlSerializer/XmlSerializerTests.cs

@@ -69,6 +69,44 @@ public static void Xml_TypeWithDateTimePropertyAsXmlTime()
         }
     }
 
+    [Fact]
+    public static void Xml_NamespaceTypeNameClashTest()
+    {
+        var serializer = new XmlSerializer(typeof(NamespaceTypeNameClashContainer));
+
+        Assert.NotNull(serializer);
+
+        var root = new NamespaceTypeNameClashContainer
+        {
+            A = new[] { new SerializationTypes.TypeNameClashA.TypeNameClash { Name = "N1" }, new SerializationTypes.TypeNameClashA.TypeNameClash { Name = "N2" } },
+            B = new[] { new SerializationTypes.TypeNameClashB.TypeNameClash { Name = "N3" } }
+        };
+
+        var xml = @"<?xml version=""1.0""?>
+        <Root xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xmlns:xsd=""http://www.w3.org/2001/XMLSchema"">
+          <A>
+            <Name>N1</Name>
+          </A>
+          <A>
+            <Name>N2</Name>
+          </A>
+          <B>
+            <Name>N3</Name>
+          </B>
+        </Root>";
+
+        var actualRoot = SerializeAndDeserialize<NamespaceTypeNameClashContainer>(root, xml);
+
+        Assert.NotNull(actualRoot);
+        Assert.NotNull(actualRoot.A);
+        Assert.NotNull(actualRoot.B);
+        Assert.Equal(root.A.Length, actualRoot.A.Length);
+        Assert.Equal(root.B.Length, actualRoot.B.Length);
+        Assert.Equal(root.A[0].Name, actualRoot.A[0].Name);
+        Assert.Equal(root.A[1].Name, actualRoot.A[1].Name);
+        Assert.Equal(root.B[0].Name, actualRoot.B[0].Name);
+    }
+
     [Fact]
     public static void Xml_ArrayAsGetSet()
     {

src/libraries/System.Runtime.Serialization.Xml/tests/SerializationTypes.cs

@@ -850,6 +850,35 @@ public class TypeWithKnownTypesOfCollectionsWithConflictingXmlName
         public object Value2 = new SimpleType[1];
 
     }
+
+    namespace TypeNameClashA
+    {
+        [System.Xml.Serialization.XmlType("TypeClashA")]
+        public class TypeNameClash
+        {
+            public string Name { get; set; }
+        }
+    }
+
+    namespace TypeNameClashB
+    {
+        [System.Xml.Serialization.XmlType("TypeClashB")]
+        public class TypeNameClash
+        {
+            public string Name { get; set; }
+        }
+    }
+
+    [System.Xml.Serialization.XmlRootAttribute("Root")]
+    [System.Xml.Serialization.XmlType("ContainerType")]
+    public class NamespaceTypeNameClashContainer
+    {
+        [System.Xml.Serialization.XmlElementAttribute("A")]
+        public TypeNameClashA.TypeNameClash[] A { get; set; }
+
+        [System.Xml.Serialization.XmlElementAttribute("B")]
+        public TypeNameClashB.TypeNameClash[] B { get; set; }
+    }
 }
 
 public class TypeWithXmlElementProperty
@@ -921,7 +950,6 @@ public class TypeWithXmlNodeArrayProperty
     public XmlNode[] CDATA { get; set; }
 }
 
-
 public class Animal
 {
     public int Age;