diff --git a/src/Metadata/Resource/Factory/ExtractorResourceMetadataCollectionFactory.php b/src/Metadata/Resource/Factory/ExtractorResourceMetadataCollectionFactory.php
index fd7abf9d70..0c4a9e6345 100644
--- a/src/Metadata/Resource/Factory/ExtractorResourceMetadataCollectionFactory.php
+++ b/src/Metadata/Resource/Factory/ExtractorResourceMetadataCollectionFactory.php
@@ -177,6 +177,9 @@ private function addGraphQlOperations(?array $data, ApiResource $resource): ApiR
             }
 
             [$key, $operation] = $this->getOperationWithDefaults($resource, $operation);
+            if (\array_key_exists($key, $operations)) {
+                throw new RuntimeException(\sprintf('GraphQL operation name "%s" is declared twice on resource "%s". GraphQL operation names must be unique, set distinct names.', $key, $resource->getClass() ?? ''));
+            }
             $operations[$key] = $operation;
         }
 
diff --git a/src/Metadata/Resource/Factory/MetadataCollectionFactoryTrait.php b/src/Metadata/Resource/Factory/MetadataCollectionFactoryTrait.php
index e4ca44459e..dc2c144f8a 100644
--- a/src/Metadata/Resource/Factory/MetadataCollectionFactoryTrait.php
+++ b/src/Metadata/Resource/Factory/MetadataCollectionFactoryTrait.php
@@ -117,6 +117,7 @@ private function buildResourceOperations(array $metadataCollection, string $reso
                 }
                 [$key, $operation] = $this->getOperationWithDefaults($resources[$index], $metadata);
                 $graphQlOperations = $resources[$index]->getGraphQlOperations();
+                $this->assertGraphQlOperationNameIsUnique($graphQlOperations ?? [], $key, $resourceClass);
                 $graphQlOperations[$key] = $operation;
                 $resources[$index] = $resources[$index]->withGraphQlOperations($graphQlOperations);
                 continue;
@@ -205,6 +206,7 @@ private function buildResourceOperations(array $metadataCollection, string $reso
                     $operation = $this->mergeOperationParameters($operation, $parameters);
                 }
 
+                $this->assertGraphQlOperationNameIsUnique($graphQlOperationsWithDefaults, $key, $resourceClass);
                 $graphQlOperationsWithDefaults[$key] = $operation;
             }
 
@@ -270,6 +272,20 @@ private function deduplicateShortNames(array $resources): array
         return $resources;
     }
 
+    /**
+     * GraphQL operations are indexed by name, a duplicate would silently replace the first one.
+     *
+     * @param array<string, mixed> $operations
+     */
+    private function assertGraphQlOperationNameIsUnique(array $operations, string $key, string $resourceClass): void
+    {
+        if (!\array_key_exists($key, $operations)) {
+            return;
+        }
+
+        throw new RuntimeException(\sprintf('GraphQL operation name "%s" is declared twice on resource "%s". GraphQL operation names must be unique, set distinct names.', $key, $resourceClass));
+    }
+
     /**
      * Two operations sharing an explicit name silently overwrite each other because
      * the operation name is the unique key (and the Symfony route name).
diff --git a/src/Metadata/Tests/Extractor/XmlExtractorTest.php b/src/Metadata/Tests/Extractor/XmlExtractorTest.php
index 1c1e8545de..c9c3e9ee6e 100644
--- a/src/Metadata/Tests/Extractor/XmlExtractorTest.php
+++ b/src/Metadata/Tests/Extractor/XmlExtractorTest.php
@@ -493,6 +493,17 @@ public function testDuplicateOperationNameFromXmlThrows(): void
         $factory->create(Comment::class);
     }
 
+    public function testDuplicateGraphQlOperationNameFromXmlThrows(): void
+    {
+        $extractor = new XmlResourceExtractor([__DIR__.'/xml/duplicate_graphql_operation_name.xml']);
+        $factory = new ExtractorResourceMetadataCollectionFactory($extractor, graphQlEnabled: true);
+
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage(\sprintf('GraphQL operation name "item_query" is declared twice on resource "%s".', Comment::class));
+
+        $factory->create(Comment::class);
+    }
+
     public function testOpenApiParametersAreAList(): void
     {
         $extractor = new XmlResourceExtractor([__DIR__.'/xml/openapi_parameters.xml']);
diff --git a/src/Metadata/Tests/Extractor/xml/duplicate_graphql_operation_name.xml b/src/Metadata/Tests/Extractor/xml/duplicate_graphql_operation_name.xml
new file mode 100644
index 0000000000..1070d86215
--- /dev/null
+++ b/src/Metadata/Tests/Extractor/xml/duplicate_graphql_operation_name.xml
@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<resources xmlns="https://api-platform.com/schema/metadata/resources-3.0"
+           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+           xsi:schemaLocation="https://api-platform.com/schema/metadata/resources-3.0
+           https://api-platform.com/schema/metadata/resources-3.0.xsd">
+    <resource class="ApiPlatform\Metadata\Tests\Fixtures\ApiResource\Comment">
+        <graphQlOperations>
+            <graphQlOperation class="ApiPlatform\Metadata\GraphQl\Query"
+                              name="item_query"
+                              security="is_granted('ROLE_ADMIN')" />
+            <graphQlOperation class="ApiPlatform\Metadata\GraphQl\Query"
+                              name="item_query" />
+        </graphQlOperations>
+    </resource>
+</resources>
diff --git a/src/Metadata/Tests/Fixtures/ApiResource/SameNameGraphQlOperationAttributes.php b/src/Metadata/Tests/Fixtures/ApiResource/SameNameGraphQlOperationAttributes.php
new file mode 100644
index 0000000000..9617e08c9e
--- /dev/null
+++ b/src/Metadata/Tests/Fixtures/ApiResource/SameNameGraphQlOperationAttributes.php
@@ -0,0 +1,25 @@
+<?php
+
+/*
+ * This file is part of the API Platform project.
+ *
+ * (c) Kévin Dunglas <dunglas@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace ApiPlatform\Metadata\Tests\Fixtures\ApiResource;
+
+use ApiPlatform\Metadata\ApiProperty;
+use ApiPlatform\Metadata\GraphQl\Query;
+
+#[Query(name: 'item_query', security: 'is_granted("ROLE_ADMIN")')]
+#[Query(name: 'item_query')]
+class SameNameGraphQlOperationAttributes
+{
+    #[ApiProperty(identifier: true)]
+    public ?string $id = null;
+}
diff --git a/src/Metadata/Tests/Fixtures/ApiResource/SameNameGraphQlOperations.php b/src/Metadata/Tests/Fixtures/ApiResource/SameNameGraphQlOperations.php
new file mode 100644
index 0000000000..1b28e250cf
--- /dev/null
+++ b/src/Metadata/Tests/Fixtures/ApiResource/SameNameGraphQlOperations.php
@@ -0,0 +1,30 @@
+<?php
+
+/*
+ * This file is part of the API Platform project.
+ *
+ * (c) Kévin Dunglas <dunglas@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace ApiPlatform\Metadata\Tests\Fixtures\ApiResource;
+
+use ApiPlatform\Metadata\ApiProperty;
+use ApiPlatform\Metadata\ApiResource;
+use ApiPlatform\Metadata\GraphQl\Query;
+
+#[ApiResource(
+    graphQlOperations: [
+        new Query(name: 'item_query', security: 'is_granted("ROLE_ADMIN")'),
+        new Query(name: 'item_query'),
+    ],
+)]
+class SameNameGraphQlOperations
+{
+    #[ApiProperty(identifier: true)]
+    public ?string $id = null;
+}
diff --git a/src/Metadata/Tests/Resource/Factory/AttributesResourceMetadataCollectionFactoryTest.php b/src/Metadata/Tests/Resource/Factory/AttributesResourceMetadataCollectionFactoryTest.php
index 1a995b3736..b1edcdb40e 100644
--- a/src/Metadata/Tests/Resource/Factory/AttributesResourceMetadataCollectionFactoryTest.php
+++ b/src/Metadata/Tests/Resource/Factory/AttributesResourceMetadataCollectionFactoryTest.php
@@ -42,6 +42,8 @@
 use ApiPlatform\Metadata\Tests\Fixtures\ApiResource\ResourceClassPropagation;
 use ApiPlatform\Metadata\Tests\Fixtures\ApiResource\ResourceClassPropagationTarget;
 use ApiPlatform\Metadata\Tests\Fixtures\ApiResource\SameNameDifferentMethodOperations;
+use ApiPlatform\Metadata\Tests\Fixtures\ApiResource\SameNameGraphQlOperationAttributes;
+use ApiPlatform\Metadata\Tests\Fixtures\ApiResource\SameNameGraphQlOperations;
 use ApiPlatform\Metadata\Tests\Fixtures\ApiResource\WithParameter;
 use ApiPlatform\Metadata\Tests\Fixtures\State\AttributeResourceProcessor;
 use ApiPlatform\Metadata\Tests\Fixtures\State\AttributeResourceProvider;
@@ -440,4 +442,24 @@ public function testDuplicateOperationNameThrows(): void
 
         $factory->create(SameNameDifferentMethodOperations::class);
     }
+
+    public function testDuplicateGraphQlOperationNameThrows(): void
+    {
+        $factory = new AttributesResourceMetadataCollectionFactory(graphQlEnabled: true);
+
+        $this->expectException(\ApiPlatform\Metadata\Exception\RuntimeException::class);
+        $this->expectExceptionMessage(\sprintf('GraphQL operation name "item_query" is declared twice on resource "%s".', SameNameGraphQlOperations::class));
+
+        $factory->create(SameNameGraphQlOperations::class);
+    }
+
+    public function testDuplicateGraphQlOperationNameOnAttributesThrows(): void
+    {
+        $factory = new AttributesResourceMetadataCollectionFactory(graphQlEnabled: true);
+
+        $this->expectException(\ApiPlatform\Metadata\Exception\RuntimeException::class);
+        $this->expectExceptionMessage(\sprintf('GraphQL operation name "item_query" is declared twice on resource "%s".', SameNameGraphQlOperationAttributes::class));
+
+        $factory->create(SameNameGraphQlOperationAttributes::class);
+    }
 }