diff --git a/containers/libreportal/frontend/components/admin/config/js/config-manager.js b/containers/libreportal/frontend/components/admin/config/js/config-manager.js
index 22cd309..24c87b3 100755
--- a/containers/libreportal/frontend/components/admin/config/js/config-manager.js
+++ b/containers/libreportal/frontend/components/admin/config/js/config-manager.js
@@ -162,8 +162,13 @@ if (typeof window.ConfigManager === 'undefined') {
         // Load configuration data
         const configData = await this.core.loadConfig(category);
         
-        // Populate sidebar with categories
-        this.sidebar.populateSidebar();
+        // Populate sidebar with categories — but only when rendering into the
+        // admin shell. A `target` means an EMBEDDED render (the backup center's
+        // Configuration tab reuses this renderer inside its own pane), where
+        // config-categories-list legitimately does not exist; populating there
+        // logged "element not found" as an error on every repaint, and the
+        // refresh coordinator repaints on every task event.
+        if (!target) this.sidebar.populateSidebar();
         
         if (Object.keys(configData).length === 0) {
           configSection.innerHTML = '<div class="no-config"><h3>No Configuration Available</h3><p>No configuration items found for this category.</p></div>';
diff --git a/containers/libreportal/frontend/core/kernel/js/spa.js b/containers/libreportal/frontend/core/kernel/js/spa.js
index a5deaab..a54e3a1 100755
--- a/containers/libreportal/frontend/core/kernel/js/spa.js
+++ b/containers/libreportal/frontend/core/kernel/js/spa.js
@@ -528,6 +528,16 @@ class LibrePortalSPAClean {
     if (document.getElementById(scriptId)) {
       return; // Already loaded
     }
+    // Also recognise tags the boot-time system loader injected: it dedupes by
+    // src and adds NO id, so the id check above cannot see its scripts. That
+    // one-way blindness is how backup-app-card.js loaded twice — boot loads it
+    // id-less, the overview's Backups tab loads it again through here, and
+    // `class BackupAppCard` redeclares with an uncaught SyntaxError. The system
+    // loader's own attribute check already covers scripts WE inject, so
+    // matching by src here closes the asymmetry for every shared file.
+    if (document.querySelector(`script[src="${src}"]`)) {
+      return;
+    }
 
     return new Promise((resolve, reject) => {
       const script = document.createElement('script');