diff --git a/docs/developer-guide/extensions/proxy-extensions.md b/docs/developer-guide/extensions/proxy-extensions.md
index 57166ef071642..cd41452fbcbe3 100644
--- a/docs/developer-guide/extensions/proxy-extensions.md
+++ b/docs/developer-guide/extensions/proxy-extensions.md
@@ -184,12 +184,11 @@ the argocd-secret with key 'some.argocd.secret.key'.
 If provided, and multiple services are configured, will have to match
 the application destination name or server to have requests properly
 forwarded to this service URL. If there are multiple backends for the
-same extension this field is required. In this case at least one of
-the two will be required: name or server. It is better to provide both
-values to avoid problems with applications unable to send requests to
-the proper backend service. If only one backend service is
-configured, this field is ignored, and all requests are forwarded to
-the configured one.
+same extension this field is required. In this case, it is necessary
+to provide both values to avoid problems with applications unable to
+send requests to the proper backend service. If only one backend
+service is configured, this field is ignored, and all requests are
+forwarded to the configured one.
 
 #### `extensions.backend.services.cluster.name` (*string*)
 (optional)
diff --git a/server/extension/extension.go b/server/extension/extension.go
index d28d3aac5dc9f..215e11a3a8bc8 100644
--- a/server/extension/extension.go
+++ b/server/extension/extension.go
@@ -640,6 +640,14 @@ func appendProxy(registry ProxyRegistry,
 		}
 		registry[key] = proxy
 	}
+	if service.Cluster.Name != "" && service.Cluster.Server != "" {
+		key := proxyKey(extName, service.Cluster.Name, service.Cluster.Server)
+		if _, exist := registry[key]; exist {
+			return fmt.Errorf("duplicated proxy configuration found for extension key %q", key)
+		}
+		registry[key] = proxy
+	}
+
 	return nil
 }
 
diff --git a/server/extension/extension_test.go b/server/extension/extension_test.go
index 3a92fcfeffb8f..7f89e90168a52 100644
--- a/server/extension/extension_test.go
+++ b/server/extension/extension_test.go
@@ -355,7 +355,8 @@ func TestCallExtension(t *testing.T) {
 
 		settings := &settings.ArgoCDSettings{
 			ExtensionConfig: map[string]string{
-				"": configYaml,
+				"ephemeral": "services:\n- url: http://some-server.com",
+				"":          configYaml,
 			},
 			Secrets: secrets,
 		}
@@ -481,11 +482,13 @@ func TestCallExtension(t *testing.T) {
 
 		response1 := "response backend 1"
 		cluster1Name := "cluster1"
+		cluster1URL := "url1"
 		beSrv1 := startBackendTestSrv(response1)
 		defer beSrv1.Close()
 
 		response2 := "response backend 2"
-		cluster2URL := "cluster2"
+		cluster2Name := "cluster2"
+		cluster2URL := "url2"
 		beSrv2 := startBackendTestSrv(response2)
 		defer beSrv2.Close()
 
@@ -493,7 +496,7 @@ func TestCallExtension(t *testing.T) {
 		f.appGetterMock.On("Get", "ns2", "app2").Return(getApp("", cluster2URL, defaultProjectName), nil)
 
 		withRbac(f, true, true)
-		withExtensionConfig(getExtensionConfigWith2Backends(extName, beSrv1.URL, cluster1Name, beSrv2.URL, cluster2URL), f)
+		withExtensionConfig(getExtensionConfigWith2Backends(extName, beSrv1.URL, cluster1Name, cluster1URL, beSrv2.URL, cluster2Name, cluster2URL), f)
 		withProject(getProjectWithDestinations("project-name", []string{cluster1Name}, []string{cluster2URL}), f)
 		withMetrics(f)
 		withUser(f, "some-user", []string{"group1", "group2"})
@@ -673,7 +676,7 @@ func TestCallExtension(t *testing.T) {
 		f.appGetterMock.On("Get", "ns1", "app1").Return(getApp(maliciousName, destinationServer, defaultProjectName), nil)
 
 		withRbac(f, true, true)
-		withExtensionConfig(getExtensionConfigWith2Backends(extName, "url1", "clusterName", "url2", "clusterURL"), f)
+		withExtensionConfig(getExtensionConfigWith2Backends(extName, "url1", "cluster1Name", "cluster1URL", "url2", "cluster2Name", "cluster2URL"), f)
 		withProject(getProjectWithDestinations("project-name", nil, []string{"srv1", destinationServer}), f)
 		withMetrics(f)
 		withUser(f, "some-user", []string{"group1", "group2"})
@@ -740,7 +743,7 @@ extensions:
 	return fmt.Sprintf(cfg, name, url)
 }
 
-func getExtensionConfigWith2Backends(name, url1, clusName, url2, clusURL string) string {
+func getExtensionConfigWith2Backends(name, url1, clus1Name, clus1URL, url2, clus2Name, clus2URL string) string {
 	cfg := `
 extensions:
 - name: %s
@@ -752,17 +755,22 @@ extensions:
         value: '$extension.auth.header'
       cluster:
         name: %s
+        server: %s
     - url: %s
       headers:
       - name: Authorization
         value: '$extension.auth.header2'
       cluster:
+        name: %s
         server: %s
+    - url: http://test.com
+      cluster:
+        name: cl1
+    - url: http://test2.com
+      cluster:
+        name: cl2
 `
-	// second extension is configured with the cluster url rather
-	// than the cluster name so we can validate that both use-cases
-	// are working
-	return fmt.Sprintf(cfg, name, url1, clusName, url2, clusURL)
+	return fmt.Sprintf(cfg, name, url1, clus1Name, clus1URL, url2, clus2Name, clus2URL)
 }
 
 func getExtensionConfigString() string {