diff --git a/extension/locales/ru.json b/extension/locales/ru.json
index 0bdc64e..880e6c7 100644
--- a/extension/locales/ru.json
+++ b/extension/locales/ru.json
@@ -189,7 +189,6 @@
   "AUDIO_OPEN_SETTINGS": "Открыть",
   "NEW_FEATURE_AUDIO": "Новое: Обработка звука — попробуйте компрессор!",
   "AUDIO_BACK": "← Назад",
-  "AUDIO_BACK": "← Назад",
   "AUDIO_PAGE_TITLE": "Настройки звука",
   "AUDIO_MASTER_TOGGLE": "Обработка звука",
   "AUDIO_COMPRESSOR": "Компрессор",
diff --git a/scripts/test-locales.js b/scripts/test-locales.js
index 00317f1..e45069c 100644
--- a/scripts/test-locales.js
+++ b/scripts/test-locales.js
@@ -55,7 +55,26 @@ console.log(`Auditing i18n locales using ${enKeys.length} baseline keys from en.
 for (const file of localeFiles) {
   const filePath = path.join(localesDir, file);
   try {
-    const dict = JSON.parse(fs.readFileSync(filePath, 'utf8'));
+    const raw = fs.readFileSync(filePath, 'utf8');
+
+    // Check for duplicate keys in raw JSON before parsing
+    const keyRe = /"(\w+)"\s*:/g;
+    const seenKeys = {};
+    let dupes = [];
+    let m;
+    while ((m = keyRe.exec(raw)) !== null) {
+      if (seenKeys[m[1]]) {
+        dupes.push(m[1]);
+      }
+      seenKeys[m[1]] = true;
+    }
+    if (dupes.length > 0) {
+      hasError = true;
+      console.error(`❌ ${file} has duplicate keys: ${[...new Set(dupes)].join(', ')}`);
+      continue;
+    }
+
+    const dict = JSON.parse(raw);
     const keys = Object.keys(dict);
 
     const missingKeys = enKeys.filter(k => !keys.includes(k));
diff --git a/scripts/test-website-locales.mjs b/scripts/test-website-locales.mjs
index 3b069bf..b4bd9b3 100644
--- a/scripts/test-website-locales.mjs
+++ b/scripts/test-website-locales.mjs
@@ -27,7 +27,26 @@ console.log(`Auditing website i18n locales using ${enKeys.length} baseline keys
 for (const file of localeFiles) {
   const filePath = path.join(localesDir, file);
   try {
-    const dict = JSON.parse(fs.readFileSync(filePath, 'utf8'));
+    const raw = fs.readFileSync(filePath, 'utf8');
+
+    // Check for duplicate keys in raw JSON before parsing
+    const keyRe = /"(\w+)"\s*:/g;
+    const seenKeys = {};
+    let dupes = [];
+    let m;
+    while ((m = keyRe.exec(raw)) !== null) {
+      if (seenKeys[m[1]]) {
+        dupes.push(m[1]);
+      }
+      seenKeys[m[1]] = true;
+    }
+    if (dupes.length > 0) {
+      hasError = true;
+      console.error(`❌ ${file} has duplicate keys: ${[...new Set(dupes)].join(', ')}`);
+      continue;
+    }
+
+    const dict = JSON.parse(raw);
     const keys = Object.keys(dict).sort();
 
     const missingKeys = enKeys.filter(k => !keys.includes(k));