diff --git a/eng/Version.Details.xml b/eng/Version.Details.xml
index 920265b037..f5813a3afc 100644
--- a/eng/Version.Details.xml
+++ b/eng/Version.Details.xml
@@ -13,21 +13,21 @@
       <Uri>https://github.com/aspnet/Blazor</Uri>
       <Sha>1eea415dd9381f7f13585fe3a5c60ce73ce65174</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.AspNetCore.Razor.Language" Version="3.1.0-preview2.19528.1">
+    <Dependency Name="Microsoft.AspNetCore.Razor.Language" Version="3.1.0-preview3.19530.1">
       <Uri>https://github.com/aspnet/AspNetCore-Tooling</Uri>
-      <Sha>d273a0f4ccfd17a50b490492929bb3617ca73c32</Sha>
+      <Sha>80dfa87c89b1cd8639653bb2dad74184c01adb9d</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.AspNetCore.Mvc.Razor.Extensions" Version="3.1.0-preview2.19528.1">
+    <Dependency Name="Microsoft.AspNetCore.Mvc.Razor.Extensions" Version="3.1.0-preview3.19530.1">
       <Uri>https://github.com/aspnet/AspNetCore-Tooling</Uri>
-      <Sha>d273a0f4ccfd17a50b490492929bb3617ca73c32</Sha>
+      <Sha>80dfa87c89b1cd8639653bb2dad74184c01adb9d</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.CodeAnalysis.Razor" Version="3.1.0-preview2.19528.1">
+    <Dependency Name="Microsoft.CodeAnalysis.Razor" Version="3.1.0-preview3.19530.1">
       <Uri>https://github.com/aspnet/AspNetCore-Tooling</Uri>
-      <Sha>d273a0f4ccfd17a50b490492929bb3617ca73c32</Sha>
+      <Sha>80dfa87c89b1cd8639653bb2dad74184c01adb9d</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.NET.Sdk.Razor" Version="3.1.0-preview2.19528.1">
+    <Dependency Name="Microsoft.NET.Sdk.Razor" Version="3.1.0-preview3.19530.1">
       <Uri>https://github.com/aspnet/AspNetCore-Tooling</Uri>
-      <Sha>d273a0f4ccfd17a50b490492929bb3617ca73c32</Sha>
+      <Sha>80dfa87c89b1cd8639653bb2dad74184c01adb9d</Sha>
     </Dependency>
     <Dependency Name="dotnet-ef" Version="3.1.0-preview2.19525.5">
       <Uri>https://github.com/aspnet/EntityFrameworkCore</Uri>
diff --git a/eng/Versions.props b/eng/Versions.props
index 33381f89b6..6e304c3fec 100644
--- a/eng/Versions.props
+++ b/eng/Versions.props
@@ -168,10 +168,10 @@
     <MicrosoftEntityFrameworkCoreToolsPackageVersion>3.1.0-preview2.19525.5</MicrosoftEntityFrameworkCoreToolsPackageVersion>
     <MicrosoftEntityFrameworkCorePackageVersion>3.1.0-preview2.19525.5</MicrosoftEntityFrameworkCorePackageVersion>
     <!-- Packages from aspnet/AspNetCore-Tooling -->
-    <MicrosoftAspNetCoreMvcRazorExtensionsPackageVersion>3.1.0-preview2.19528.1</MicrosoftAspNetCoreMvcRazorExtensionsPackageVersion>
-    <MicrosoftAspNetCoreRazorLanguagePackageVersion>3.1.0-preview2.19528.1</MicrosoftAspNetCoreRazorLanguagePackageVersion>
-    <MicrosoftCodeAnalysisRazorPackageVersion>3.1.0-preview2.19528.1</MicrosoftCodeAnalysisRazorPackageVersion>
-    <MicrosoftNETSdkRazorPackageVersion>3.1.0-preview2.19528.1</MicrosoftNETSdkRazorPackageVersion>
+    <MicrosoftAspNetCoreMvcRazorExtensionsPackageVersion>3.1.0-preview3.19530.1</MicrosoftAspNetCoreMvcRazorExtensionsPackageVersion>
+    <MicrosoftAspNetCoreRazorLanguagePackageVersion>3.1.0-preview3.19530.1</MicrosoftAspNetCoreRazorLanguagePackageVersion>
+    <MicrosoftCodeAnalysisRazorPackageVersion>3.1.0-preview3.19530.1</MicrosoftCodeAnalysisRazorPackageVersion>
+    <MicrosoftNETSdkRazorPackageVersion>3.1.0-preview3.19530.1</MicrosoftNETSdkRazorPackageVersion>
   </PropertyGroup>
   <!--
 
diff --git a/src/Components/Components/src/Rendering/RenderTreeBuilder.cs b/src/Components/Components/src/Rendering/RenderTreeBuilder.cs
index 6876c97f0d..f8a28273e4 100644
--- a/src/Components/Components/src/Rendering/RenderTreeBuilder.cs
+++ b/src/Components/Components/src/Rendering/RenderTreeBuilder.cs
@@ -581,6 +581,14 @@ namespace Microsoft.AspNetCore.Components.Rendering
         /// <param name="sequence">An integer that represents the position of the instruction in the source code.</param>
         public void OpenRegion(int sequence)
         {
+            // We are entering a new scope, since we track the "duplicate attributes" per
+            // element/component we might need to clean them up now.
+            if (_hasSeenAddMultipleAttributes)
+            {
+                var indexOfLastElementOrComponent = _openElementIndices.Peek();
+                ProcessDuplicateAttributes(first: indexOfLastElementOrComponent + 1);
+            }
+
             _openElementIndices.Push(_entries.Count);
             Append(RenderTreeFrame.Region(sequence));
         }
diff --git a/src/Components/Components/test/Rendering/RenderTreeBuilderTest.cs b/src/Components/Components/test/Rendering/RenderTreeBuilderTest.cs
index 7dfce8a79c..31364dca00 100644
--- a/src/Components/Components/test/Rendering/RenderTreeBuilderTest.cs
+++ b/src/Components/Components/test/Rendering/RenderTreeBuilderTest.cs
@@ -298,6 +298,39 @@ namespace Microsoft.AspNetCore.Components.Rendering
                 frame => AssertFrame.Attribute(frame, "attribute7", "the end"));
         }
 
+        [Fact]
+        public void CanAddMultipleAttributes_WithChildRegion()
+        {
+            // This represents bug https://github.com/aspnet/AspNetCore/issues/16570
+            // If a sequence of attributes is terminated by a call to builder.OpenRegion,
+            // then the attribute deduplication logic wasn't working correctly
+
+            // Arrange
+            var builder = new RenderTreeBuilder();
+
+            // Act
+            builder.OpenElement(0, "myelement");
+            builder.AddAttribute(0, "attribute1", "value1");
+            builder.AddMultipleAttributes(1, new Dictionary<string, object>()
+            {
+                { "attribute1", "value2" },
+            });
+            builder.OpenRegion(2);
+            builder.OpenElement(3, "child");
+            builder.CloseElement();
+            builder.CloseRegion();
+            builder.CloseElement();
+
+            // Assert
+            var frames = builder.GetFrames().AsEnumerable().ToArray();
+            Assert.Collection(
+                frames,
+                frame => AssertFrame.Element(frame, "myelement", 4),
+                frame => AssertFrame.Attribute(frame, "attribute1", "value2"),
+                frame => AssertFrame.Region(frame, 2, 2),
+                frame => AssertFrame.Element(frame, "child", 1, 3));
+        }
+
         [Fact]
         public void CanAddMultipleAttributes_DictionaryObject()
         {