diff --git a/CHANGELOG.md b/CHANGELOG.md
index ab8423e..f21716b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,27 @@ All notable changes to WooCommerce Tier and Package Prices will be documented in
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [1.1.19] - 2025-12-22
+
+### Fixed
+
+- Settings page still appearing twice despite instance caching
+- Duplicate detection using strict instance comparison failing for different object instances
+
+### Changed
+
+- Enhanced duplicate detection to check by class type and ID instead of instance
+- Added `instanceof WC_TPP_Settings` check
+- Added ID-based duplicate detection via `get_id()` method and direct property access
+- Multiple fallback checks to catch duplicates regardless of instance identity
+
+### Technical Details
+
+- Previous strict comparison (`===`) failed when different instances of same class existed
+- New approach checks: instanceof, get_id() method, and id property
+- Returns early if any settings page with ID 'tier_package_prices' found
+- Prevents duplicates even if settings instance recreated or serialized
+
 ## [1.1.18] - 2025-12-22
 
 ### Fixed
diff --git a/composer.json b/composer.json
index d8c9991..c835adb 100644
--- a/composer.json
+++ b/composer.json
@@ -1,7 +1,7 @@
 {
     "name": "magdev/wc-tier-package-prices",
     "description": "WooCommerce plugin for tier pricing and package prices with Twig templates",
-    "version": "1.1.18",
+    "version": "1.1.19",
     "type": "wordpress-plugin",
     "license": "GPL-2.0-or-later",
     "authors": [
diff --git a/includes/class-wc-tpp-admin.php b/includes/class-wc-tpp-admin.php
index cded785..e89794a 100644
--- a/includes/class-wc-tpp-admin.php
+++ b/includes/class-wc-tpp-admin.php
@@ -35,8 +35,21 @@ if (!class_exists('WC_TPP_Admin')) {
         }
 
         // Check if our settings page is already in the array to prevent duplicates
+        // Check by class type and ID instead of instance comparison
         foreach ($settings as $settings_page) {
-            if ($settings_page === self::$settings_instance) {
+            if ($settings_page instanceof WC_TPP_Settings) {
+                return $settings;
+            }
+            // Also check by ID property if it's a WC_Settings_Page
+            if (is_object($settings_page) &&
+                method_exists($settings_page, 'get_id') &&
+                $settings_page->get_id() === 'tier_package_prices') {
+                return $settings;
+            }
+            // Check id property directly
+            if (is_object($settings_page) &&
+                isset($settings_page->id) &&
+                $settings_page->id === 'tier_package_prices') {
                 return $settings;
             }
         }
diff --git a/wc-tier-and-package-prices.php b/wc-tier-and-package-prices.php
index ae7b7ff..69ea88b 100644
--- a/wc-tier-and-package-prices.php
+++ b/wc-tier-and-package-prices.php
@@ -4,7 +4,7 @@
  * Plugin Name: WooCommerce Tier and Package Prices
  * Plugin URI: https://src.bundespruefstelle.ch/magdev/wc-tier-package-prices
  * Description: Add tier pricing and package prices to WooCommerce products with configurable quantities at fixed prices
- * Version: 1.1.18
+ * Version: 1.1.19
  * Author: Marco Graetsch
  * Author URI: https://src.bundespruefstelle.ch/magdev
  * Text Domain: wc-tier-package-prices
@@ -23,7 +23,7 @@ if (!defined('ABSPATH')) {
 
 // Define plugin constants
 if (!defined('WC_TPP_VERSION')) {
-    define('WC_TPP_VERSION', '1.1.18');
+    define('WC_TPP_VERSION', '1.1.19');
 }
 if (!defined('WC_TPP_PLUGIN_DIR')) {
     define('WC_TPP_PLUGIN_DIR', plugin_dir_path(__FILE__));