Fix so that if two paraters have the same type and different defaults they are properly resolved.

Author: Keboo

src/System.CommandLine.DragonFruit.Tests/ConfigureFromMethodTests.cs

@@ -235,6 +235,17 @@ public async Task Method_parameters_on_the_invoked_member_method_are_bound_to_ma
             _receivedValues.Should().BeEquivalentTo(true);
         }
 
+        [Fact]
+        public async Task Method_with_multiple_parameters_with_default_values_are_resolved_correctly()
+        {
+            var command = new Command("test");
+            command.ConfigureFromMethod(GetMethodInfo(nameof(Method_with_multiple_default_values)), this);
+
+            await command.InvokeAsync("");
+
+            _receivedValues.Should().BeEquivalentTo(1, 2);
+        }
+
         internal void Method_taking_bool(bool value = false)
         {
             _receivedValues = new object[] { value };
@@ -294,6 +305,11 @@ internal void Method_having_FileInfo_array_args(string stringOption, int intOpti
         {
         }
 
+        internal void Method_with_multiple_default_values(int firstValue = 1, int secondValue = 2)
+        {
+            _receivedValues = new object[] { firstValue, secondValue };
+        }
+
         private MethodInfo GetMethodInfo(string name)
         {
             return typeof(ConfigureFromMethodTests)

src/System.CommandLine.DragonFruit/CommandLine.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System.Collections.Generic;
@@ -265,9 +265,9 @@ internal static string BuildAlias(string parameterName)
                        : $"-{parameterName.ToLowerInvariant()}";
         }
 
-        public static IEnumerable<Option> BuildOptions(this MethodInfo type)
+        public static IEnumerable<Option> BuildOptions(this MethodInfo method)
         {
-            var descriptor = HandlerDescriptor.FromMethodInfo(type);
+            var descriptor = HandlerDescriptor.FromMethodInfo(method);
 
             var omittedTypes = new[]
                                {

src/System.CommandLine/Binding/BindingContext.cs

@@ -53,10 +53,14 @@ public IConsole Console
         public void AddModelBinder(ModelBinder binder) => 
             _modelBindersByValueDescriptor.Add(binder.ValueDescriptor.ValueType, binder);
 
-        public ModelBinder GetModelBinder(IValueDescriptor valueDescriptor) =>
-            _modelBindersByValueDescriptor.GetOrAdd(
-                valueDescriptor.ValueType, 
-                _ => new ModelBinder(valueDescriptor));
+        public ModelBinder GetModelBinder(IValueDescriptor valueDescriptor)
+        {
+            if (_modelBindersByValueDescriptor.TryGetValue(valueDescriptor.ValueType, out ModelBinder binder))
+            {
+                return binder;
+            }
+            return new ModelBinder(valueDescriptor);
+        }
 
         public void AddService(Type serviceType, Func<IServiceProvider, object> factory)
         {