diff --git a/release_notes.md b/release_notes.md
index 7333dc06a..3babbb06b 100644
--- a/release_notes.md
+++ b/release_notes.md
@@ -5,10 +5,12 @@
 ### New Features
 
 - Fail fast if extendedSessionsEnabled set to 'true' for the worker type that doesn't support extended sessions (https://github.com/Azure/azure-functions-durable-extension/pull/2732).
+- Added an `IFunctionsWorkerApplicationBuilder.ConfigureDurableExtension()` extension method for cases where auto-registration does not work (no source gen running). (#2950)
 
 ### Bug Fixes
 
 - Fix custom connection name not working when using IDurableClientFactory.CreateClient() - contributed by [@hctan](https://github.com/hctan)
+- Made durable extension for isolated worker configuration idempotent, allowing multiple calls safely. (#2950)
 
 ### Breaking Changes
 
diff --git a/src/Worker.Extensions.DurableTask/DurableTaskExtensionStartup.cs b/src/Worker.Extensions.DurableTask/DurableTaskExtensionStartup.cs
index 626acd6bf..af7bab017 100644
--- a/src/Worker.Extensions.DurableTask/DurableTaskExtensionStartup.cs
+++ b/src/Worker.Extensions.DurableTask/DurableTaskExtensionStartup.cs
@@ -1,20 +1,8 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
-using System;
-using Azure.Core.Serialization;
 using Microsoft.Azure.Functions.Worker.Core;
 using Microsoft.Azure.Functions.Worker.Extensions.DurableTask;
-using Microsoft.DurableTask;
-using Microsoft.DurableTask.Client;
-using Microsoft.DurableTask.Converters;
-using Microsoft.DurableTask.Worker;
-using Microsoft.DurableTask.Worker.Shims;
-using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.DependencyInjection.Extensions;
-using Microsoft.Extensions.Hosting;
-using Microsoft.Extensions.Logging;
-using Microsoft.Extensions.Options;
 
 [assembly: WorkerExtensionStartup(typeof(DurableTaskExtensionStartup))]
 
@@ -28,49 +16,6 @@ public sealed class DurableTaskExtensionStartup : WorkerExtensionStartup
     /// <inheritdoc/>
     public override void Configure(IFunctionsWorkerApplicationBuilder applicationBuilder)
     {
-        applicationBuilder.Services.AddSingleton<FunctionsDurableClientProvider>();
-        applicationBuilder.Services.AddOptions<DurableTaskClientOptions>()
-            .Configure(options => options.EnableEntitySupport = true)
-            .PostConfigure<IServiceProvider>((opt, sp) =>
-            {
-                if (GetConverter(sp) is DataConverter converter)
-                {
-                    opt.DataConverter = converter;
-                }
-            });
-
-        applicationBuilder.Services.AddOptions<DurableTaskWorkerOptions>()
-            .Configure(options => options.EnableEntitySupport = true)
-            .PostConfigure<IServiceProvider>((opt, sp) =>
-            {
-                if (GetConverter(sp) is DataConverter converter)
-                {
-                    opt.DataConverter = converter;
-                }
-            });
-
-        applicationBuilder.Services.TryAddSingleton(sp =>
-        {
-            DurableTaskWorkerOptions options = sp.GetRequiredService<IOptions<DurableTaskWorkerOptions>>().Value;
-            ILoggerFactory factory = sp.GetRequiredService<ILoggerFactory>();
-            return new DurableTaskShimFactory(options, factory); // For GrpcOrchestrationRunner
-        });
-
-        applicationBuilder.Services.Configure<WorkerOptions>(o =>
-        {
-            o.InputConverters.Register<OrchestrationInputConverter>();
-        });
-
-        applicationBuilder.UseMiddleware<DurableTaskFunctionsMiddleware>();
-    }
-
-    private static DataConverter? GetConverter(IServiceProvider services)
-    {
-        // We intentionally do not consider a DataConverter in the DI provider, or if one was already set. This is to
-        // ensure serialization is consistent with the rest of Azure Functions. This is particularly important because
-        // TaskActivity bindings use ObjectSerializer directly for the time being. Due to this, allowing DataConverter
-        // to be set separately from ObjectSerializer would give an inconsistent serialization solution.
-        WorkerOptions? worker = services.GetRequiredService<IOptions<WorkerOptions>>()?.Value;
-        return worker?.Serializer is not null ? new ObjectConverterShim(worker.Serializer) : null;
+        applicationBuilder.ConfigureDurableExtension();
     }
 }
diff --git a/src/Worker.Extensions.DurableTask/FunctionsWorkerApplicationBuilderExtensions.cs b/src/Worker.Extensions.DurableTask/FunctionsWorkerApplicationBuilderExtensions.cs
new file mode 100644
index 000000000..642446dd4
--- /dev/null
+++ b/src/Worker.Extensions.DurableTask/FunctionsWorkerApplicationBuilderExtensions.cs
@@ -0,0 +1,125 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using System;
+using System.Linq;
+using Azure.Core.Serialization;
+using Microsoft.Azure.Functions.Worker.Core;
+using Microsoft.Azure.Functions.Worker.Extensions.DurableTask;
+using Microsoft.DurableTask;
+using Microsoft.DurableTask.Client;
+using Microsoft.DurableTask.Converters;
+using Microsoft.DurableTask.Worker;
+using Microsoft.DurableTask.Worker.Shims;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Options;
+
+namespace Microsoft.Azure.Functions.Worker;
+
+/// <summary>
+/// Extensions for <see cref="IFunctionsWorkerApplicationBuilder"/>.
+/// </summary>
+public static class FunctionsWorkerApplicationBuilderExtensions
+{
+    /// <summary>
+    /// Configures the Durable Functions extension for the worker.
+    /// </summary>
+    /// <param name="builder">The builder to configure.</param>
+    /// <returns>The <paramref name="builder"/> for call chaining.</returns>
+    public static IFunctionsWorkerApplicationBuilder ConfigureDurableExtension(this IFunctionsWorkerApplicationBuilder builder)
+    {
+        if (builder is null)
+        {
+            throw new ArgumentNullException(nameof(builder));
+        }
+
+        builder.Services.TryAddSingleton<FunctionsDurableClientProvider>();
+        builder.Services.TryAddEnumerable(
+            ServiceDescriptor.Singleton<IConfigureOptions<DurableTaskClientOptions>, ConfigureClientOptions>());
+        builder.Services.TryAddEnumerable(
+            ServiceDescriptor.Singleton<IPostConfigureOptions<DurableTaskClientOptions>, PostConfigureClientOptions>());
+        builder.Services.TryAddEnumerable(
+            ServiceDescriptor.Singleton<IConfigureOptions<DurableTaskWorkerOptions>, ConfigureWorkerOptions>());
+        builder.Services.TryAddEnumerable(
+            ServiceDescriptor.Singleton<IPostConfigureOptions<DurableTaskWorkerOptions>, PostConfigureWorkerOptions>());
+
+        builder.Services.TryAddSingleton(sp =>
+        {
+            DurableTaskWorkerOptions options = sp.GetRequiredService<IOptions<DurableTaskWorkerOptions>>().Value;
+            ILoggerFactory factory = sp.GetRequiredService<ILoggerFactory>();
+            return new DurableTaskShimFactory(options, factory); // For GrpcOrchestrationRunner
+        });
+
+        builder.Services.TryAddEnumerable(
+            ServiceDescriptor.Singleton<IConfigureOptions<WorkerOptions>, ConfigureInputConverter>());
+        if (!builder.Services.Any(d => d.ServiceType == typeof(DurableTaskFunctionsMiddleware)))
+        {
+            builder.UseMiddleware<DurableTaskFunctionsMiddleware>();
+        }
+
+        return builder;
+    }
+
+    private class ConfigureInputConverter : IConfigureOptions<WorkerOptions>
+    {
+        public void Configure(WorkerOptions options)
+        {
+            options.InputConverters.Register<OrchestrationInputConverter>();
+        }
+    }
+
+    private class ConfigureClientOptions : IConfigureOptions<DurableTaskClientOptions>
+    {
+        public void Configure(DurableTaskClientOptions options)
+        {
+            options.EnableEntitySupport = true;
+        }
+    }
+
+    private class PostConfigureClientOptions : IPostConfigureOptions<DurableTaskClientOptions>
+    {
+        readonly IOptionsMonitor<WorkerOptions> workerOptions;
+
+        public PostConfigureClientOptions(IOptionsMonitor<WorkerOptions> workerOptions)
+        {
+            this.workerOptions = workerOptions;
+        }
+
+        public void PostConfigure(string name, DurableTaskClientOptions options)
+        {
+            if (this.workerOptions.Get(name).Serializer is { } serializer)
+            {
+                options.DataConverter = new ObjectConverterShim(serializer);
+            }
+        }
+    }
+
+    private class ConfigureWorkerOptions : IConfigureOptions<DurableTaskWorkerOptions>
+    {
+        public void Configure(DurableTaskWorkerOptions options)
+        {
+            options.EnableEntitySupport = true;
+        }
+    }
+
+    private class PostConfigureWorkerOptions : IPostConfigureOptions<DurableTaskWorkerOptions>
+    {
+        readonly IOptionsMonitor<WorkerOptions> workerOptions;
+
+        public PostConfigureWorkerOptions(IOptionsMonitor<WorkerOptions> workerOptions)
+        {
+            this.workerOptions = workerOptions;
+        }
+
+        public void PostConfigure(string name, DurableTaskWorkerOptions options)
+        {
+            if (this.workerOptions.Get(name).Serializer is { } serializer)
+            {
+                options.DataConverter = new ObjectConverterShim(serializer);
+            }
+        }
+    }
+}