diff --git a/src/ServiceManager.php b/src/ServiceManager.php
index d2604e95..a943150a 100644
--- a/src/ServiceManager.php
+++ b/src/ServiceManager.php
@@ -21,9 +21,9 @@
 use ProxyManager\GeneratorStrategy\EvaluatingGeneratorStrategy;
 use ProxyManager\GeneratorStrategy\FileWriterGeneratorStrategy;
 use Psr\Container\ContainerInterface;
+use Laminas\Stdlib\ArrayUtils;
 
 use function array_intersect;
-use function array_merge_recursive;
 use function class_exists;
 use function get_class;
 use function gettype;
@@ -363,7 +363,7 @@ public function configure(array $config)
         }
 
         if (isset($config['delegators'])) {
-            $this->delegators = array_merge_recursive($this->delegators, $config['delegators']);
+            $this->mergeDelegators($config['delegators']);
         }
 
         if (isset($config['shared'])) {
@@ -384,7 +384,7 @@ public function configure(array $config)
         // If lazy service configuration was provided, reset the lazy services
         // delegator factory.
         if (isset($config['lazy_services']) && ! empty($config['lazy_services'])) {
-            $this->lazyServices          = array_merge_recursive($this->lazyServices, $config['lazy_services']);
+            $this->lazyServices          = ArrayUtils::merge($this->lazyServices, $config['lazy_services']);
             $this->lazyServicesDelegator = null;
         }
 
@@ -737,6 +737,32 @@ private function createLazyServiceDelegatorFactory()
         return $this->lazyServicesDelegator;
     }
 
+    /**
+     * Merge delegators avoiding multiple same delegators for the same service.
+     * It works with strings and class instances.
+     * It's not possible to de-duple anonymous functions
+     *
+     * @param string[][]|Factory\DelegatorFactoryInterface[][] $config
+     * @return string[][]|Factory\DelegatorFactoryInterface[][]
+     */
+    private function mergeDelegators(array $config)
+    {
+        foreach ($config as $key => $delegators) {
+            if (! array_key_exists($key, $this->delegators)) {
+                $this->delegators[$key] = $delegators;
+                continue;
+            }
+
+            foreach ($delegators as $delegator) {
+                if (! in_array($delegator, $this->delegators[$key], true)) {
+                    $this->delegators[$key][] = $delegator;
+                }
+            }
+        }
+
+        return $this->delegators;
+    }
+
     /**
      * Create aliases and factories for invokable classes.
      *
diff --git a/test/ServiceManagerTest.php b/test/ServiceManagerTest.php
index f75440af..5051f241 100644
--- a/test/ServiceManagerTest.php
+++ b/test/ServiceManagerTest.php
@@ -15,6 +15,7 @@
 use Laminas\ServiceManager\ServiceManager;
 use LaminasTest\ServiceManager\TestAsset\InvokableObject;
 use LaminasTest\ServiceManager\TestAsset\SimpleServiceManager;
+use Laminas\ServiceManager\Proxy\LazyServiceFactory;
 use PHPUnit\Framework\TestCase;
 use Psr\Container\ContainerInterface;
 use stdClass;
@@ -364,4 +365,51 @@ public function testResolvedAliasNoMatchingAbstractFactoryReturnsFalse()
 
         self::assertFalse($serviceManager->has('Alias'));
     }
+
+    /**
+     * @group #3
+     * @see https://github.com/laminas/laminas-servicemanager/issues/3
+     */
+    public function testConfiguringADelegatorMultipleTimesDoesNotLeadToDuplicateDelegatorCalls()
+    {
+        $delegatorFactory = function (
+            ContainerInterface $container,
+            $name,
+            callable $callback
+        ) {
+            /** @var InvokableObject $instance */
+            $instance = $callback();
+            $options = $instance->getOptions();
+            $inc = $options['inc'] ?? 0;
+            return new InvokableObject(['inc' => ++$inc]);
+        };
+
+        $config = [
+            'factories' => [
+                'Foo' => function () {
+                    return new InvokableObject();
+                },
+            ],
+            'delegators' => [
+                'Foo' => [
+                    $delegatorFactory,
+                    LazyServiceFactory::class,
+                ],
+            ],
+            'lazy_services' => [
+                'class_map' => [
+                    'Foo' => InvokableObject::class,
+                ],
+            ],
+        ];
+
+        $serviceManager = new ServiceManager($config);
+        $serviceManager->configure($config);
+
+        /** @var InvokableObject $instance */
+        $instance = $serviceManager->get('Foo');
+
+        self::assertInstanceOf(InvokableObject::class, $instance);
+        self::assertSame(1, $instance->getOptions()['inc']);
+    }
 }