diff --git a/app/Support/BackUrl.php b/app/Support/BackUrl.php
index 1b8817b..706a58e 100644
--- a/app/Support/BackUrl.php
+++ b/app/Support/BackUrl.php
@@ -176,6 +176,11 @@ class BackUrl
      */
     public static function withBackFirstAndFragment(string $path, string $safeBackForLinks = '', string $fragment = ''): string
     {
+        // 若调用方传入了 path 自带 fragment，同时又传入 fragment 参数，避免出现 "#old#new"。
+        if ((string) $fragment !== '' && str_contains((string) $path, '#')) {
+            [$path] = explode('#', (string) $path, 2);
+        }
+
         $url = self::withBackFirst($path, $safeBackForLinks);
 
         $fragment = ltrim((string) $fragment, '#');
diff --git a/tests/Unit/BackUrlWithBackFirstAndFragmentOverridesExistingFragmentTest.php b/tests/Unit/BackUrlWithBackFirstAndFragmentOverridesExistingFragmentTest.php
new file mode 100644
index 0000000..8eb8ab5
--- /dev/null
+++ b/tests/Unit/BackUrlWithBackFirstAndFragmentOverridesExistingFragmentTest.php
@@ -0,0 +1,20 @@
+<?php
+
+namespace Tests\Unit;
+
+use App\Support\BackUrl;
+use Illuminate\Support\Arr;
+use Tests\TestCase;
+
+class BackUrlWithBackFirstAndFragmentOverridesExistingFragmentTest extends TestCase
+{
+    public function test_with_back_first_and_fragment_should_override_fragment_in_path_when_fragment_param_is_provided(): void
+    {
+        $back = '/admin/platform-orders/2';
+        $backQuery = Arr::query(['back' => $back]);
+
+        $url = BackUrl::withBackFirstAndFragment('/admin/site-subscriptions/2#old', $back, 'new');
+
+        $this->assertSame('/admin/site-subscriptions/2?' . $backQuery . '#new', $url);
+    }
+}