Replace URL and query parameter instead of adding one more with the s…

…ame name

src/RestSharp/Request/RestRequestExtensions.Query.cs

@@ -26,7 +26,7 @@ public static partial class RestRequestExtensions {
         /// <param name="encode">Encode the value or not, default true</param>
         /// <returns></returns>
         public RestRequest AddQueryParameter(string name, string? value, bool encode = true)
-            => request.AddParameter(new QueryParameter(name, value, encode));
+            => request.AddOrUpdateParameter(new QueryParameter(name, value, encode));
 
         /// <summary>
         /// Adds a query string parameter to the request. The request resource should not contain any placeholders for this parameter.

src/RestSharp/Request/RestRequestExtensions.Url.cs

@@ -26,7 +26,7 @@ public static partial class RestRequestExtensions {
         /// <param name="encode">Encode the value or not, default true</param>
         /// <returns></returns>
         public RestRequest AddUrlSegment(string name, string? value, bool encode = true)
-            => request.AddParameter(new UrlSegmentParameter(name, value, encode));
+            => request.AddOrUpdateParameter(new UrlSegmentParameter(name, value, encode));
 
         /// <summary>
         /// Adds a URL segment parameter to the request. The resource URL must have a placeholder for the parameter for it to work.

test/RestSharp.Tests/Parameters/UrlSegmentTests.cs

@@ -54,20 +54,33 @@ public void UrlSegmentParameter_WithValueWithEncodedSlash_WillReplaceEncodedSlas
         var urlSegmentParameter = new UrlSegmentParameter("foo", inputValue);
         urlSegmentParameter.Value.Should().BeEquivalentTo("bar/BAR");
     }
-    
+
     [Theory]
     [InlineData("bar%2fBAR")]
     [InlineData("bar%2FBAR")]
     public void UrlSegmentParameter_WithValueWithEncodedSlash_CanReplaceEncodedSlash(string inputValue) {
         var urlSegmentParameter = new UrlSegmentParameter("foo", inputValue, replaceEncodedSlash: true);
         urlSegmentParameter.Value.Should().BeEquivalentTo("bar/BAR");
     }
-    
+
     [Theory]
     [InlineData("bar%2fBAR")]
     [InlineData("bar%2FBAR")]
     public void UrlSegmentParameter_WithValueWithEncodedSlash_CanLeaveEncodedSlash(string inputValue) {
         var urlSegmentParameter = new UrlSegmentParameter("foo", inputValue, replaceEncodedSlash: false);
         urlSegmentParameter.Value.Should().BeEquivalentTo(inputValue);
     }
+
+    [Fact]
+    public void AddSameUrlSegmentTwice_ShouldReplaceFirst() {
+        var client  = new RestClient();
+        var request = new RestRequest("https://api.example.com/orgs/{segment}/something");
+        request.AddUrlSegment("segment", 1);
+        var url1 = client.BuildUri(request);
+        request.AddUrlSegment("segment", 2);
+        var url2 = client.BuildUri(request);
+
+        url1.AbsolutePath.Should().Be("/orgs/1/something");
+        url2.AbsolutePath.Should().Be("/orgs/2/something");
+    }
 }