diff --git a/src/Symfony/Component/Config/Definition/BaseNode.php b/src/Symfony/Component/Config/Definition/BaseNode.php
index f3ae891bad392..3d7fd85603355 100644
--- a/src/Symfony/Component/Config/Definition/BaseNode.php
+++ b/src/Symfony/Component/Config/Definition/BaseNode.php
@@ -26,7 +26,7 @@ abstract class BaseNode implements NodeInterface
 {
     const DEFAULT_PATH_SEPARATOR = '.';
 
-    private static $placeholderUniquePrefix;
+    private static $placeholderUniquePrefixes = [];
     private static $placeholders = [];
 
     protected $name;
@@ -74,7 +74,7 @@ public static function setPlaceholder(string $placeholder, array $values): void
     }
 
     /**
-     * Sets a common prefix for dynamic placeholder values.
+     * Adds a common prefix for dynamic placeholder values.
      *
      * Matching configuration values will be skipped from being processed and are returned as is, thus preserving the
      * placeholder. An exact match provided by {@see setPlaceholder()} might take precedence.
@@ -83,7 +83,7 @@ public static function setPlaceholder(string $placeholder, array $values): void
      */
     public static function setPlaceholderUniquePrefix(string $prefix): void
     {
-        self::$placeholderUniquePrefix = $prefix;
+        self::$placeholderUniquePrefixes[] = $prefix;
     }
 
     /**
@@ -93,7 +93,7 @@ public static function setPlaceholderUniquePrefix(string $prefix): void
      */
     public static function resetPlaceholders(): void
     {
-        self::$placeholderUniquePrefix = null;
+        self::$placeholderUniquePrefixes = [];
         self::$placeholders = [];
     }
 
@@ -513,8 +513,10 @@ private static function resolvePlaceholderValue($value)
                 return self::$placeholders[$value];
             }
 
-            if (self::$placeholderUniquePrefix && 0 === strpos($value, self::$placeholderUniquePrefix)) {
-                return [];
+            foreach (self::$placeholderUniquePrefixes as $placeholderUniquePrefix) {
+                if (0 === strpos($value, $placeholderUniquePrefix)) {
+                    return [];
+                }
             }
         }
 
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/MergeExtensionConfigurationPass.php b/src/Symfony/Component/DependencyInjection/Compiler/MergeExtensionConfigurationPass.php
index 264dd8046c819..7fe14a9f4ccd0 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/MergeExtensionConfigurationPass.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/MergeExtensionConfigurationPass.php
@@ -79,11 +79,11 @@ public function process(ContainerBuilder $container)
                     $container->getParameterBag()->mergeEnvPlaceholders($resolvingBag);
                 }
 
-                throw $e;
-            } finally {
                 if ($configAvailable) {
                     BaseNode::resetPlaceholders();
                 }
+
+                throw $e;
             }
 
             if ($resolvingBag instanceof MergeExtensionConfigurationParameterBag) {
@@ -95,6 +95,10 @@ public function process(ContainerBuilder $container)
             $container->getParameterBag()->add($parameters);
         }
 
+        if ($configAvailable) {
+            BaseNode::resetPlaceholders();
+        }
+
         $container->addDefinitions($definitions);
         $container->addAliases($aliases);
     }
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Compiler/MergeExtensionConfigurationPassTest.php b/src/Symfony/Component/DependencyInjection/Tests/Compiler/MergeExtensionConfigurationPassTest.php
index d5db48cc30645..a2cb3bda5ed96 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Compiler/MergeExtensionConfigurationPassTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Compiler/MergeExtensionConfigurationPassTest.php
@@ -12,6 +12,7 @@
 namespace Symfony\Component\DependencyInjection\Tests\Compiler;
 
 use PHPUnit\Framework\TestCase;
+use Symfony\Component\Config\Definition\BaseNode;
 use Symfony\Component\Config\Definition\Builder\TreeBuilder;
 use Symfony\Component\Config\Definition\ConfigurationInterface;
 use Symfony\Component\Config\Resource\FileResource;
@@ -128,6 +129,23 @@ public function testThrowingExtensionsGetMergedBag()
 
         $this->assertSame(['FOO'], array_keys($container->getParameterBag()->getEnvPlaceholders()));
     }
+
+    public function testReuseEnvPlaceholderGeneratedByPreviousExtension()
+    {
+        if (!property_exists(BaseNode::class, 'placeholderUniquePrefixes')) {
+            $this->markTestSkipped('This test requires symfony/config ^4.4.11|^5.0.11|^5.1.3');
+        }
+
+        $container = new ContainerBuilder();
+        $container->registerExtension(new FooExtension());
+        $container->registerExtension(new TestCccExtension());
+        $container->prependExtensionConfig('foo', ['bool_node' => '%env(bool:MY_ENV_VAR)%']);
+        $container->prependExtensionConfig('test_ccc', ['bool_node' => '%env(bool:MY_ENV_VAR)%']);
+
+        (new MergeExtensionConfigurationPass())->process($container);
+
+        $this->addToAssertionCount(1);
+    }
 }
 
 class FooConfiguration implements ConfigurationInterface
@@ -139,6 +157,7 @@ public function getConfigTreeBuilder(): TreeBuilder
             ->children()
                 ->scalarNode('bar')->end()
                 ->scalarNode('baz')->end()
+                ->booleanNode('bool_node')->end()
             ->end();
 
         return $treeBuilder;
@@ -166,6 +185,8 @@ public function load(array $configs, ContainerBuilder $container)
             $container->getParameterBag()->get('env(BOZ)');
             $container->resolveEnvPlaceholders($config['baz']);
         }
+
+        $container->setParameter('foo.param', 'ccc');
     }
 }
 
@@ -194,3 +215,36 @@ public function load(array $configs, ContainerBuilder $container)
         throw new \Exception();
     }
 }
+
+final class TestCccConfiguration implements ConfigurationInterface
+{
+    public function getConfigTreeBuilder(): TreeBuilder
+    {
+        $treeBuilder = new TreeBuilder('test_ccc');
+        $treeBuilder->getRootNode()
+            ->children()
+                ->booleanNode('bool_node')->end()
+            ->end();
+
+        return $treeBuilder;
+    }
+}
+
+final class TestCccExtension extends Extension
+{
+    public function getAlias(): string
+    {
+        return 'test_ccc';
+    }
+
+    public function getConfiguration(array $config, ContainerBuilder $container): ?ConfigurationInterface
+    {
+        return new TestCccConfiguration();
+    }
+
+    public function load(array $configs, ContainerBuilder $container)
+    {
+        $configuration = $this->getConfiguration($configs, $container);
+        $this->processConfiguration($configuration, $configs);
+    }
+}