diff --git a/tests/json.test.js b/tests/json.test.js
index 80d83c9ab..16dd360a2 100644
--- a/tests/json.test.js
+++ b/tests/json.test.js
@@ -35,7 +35,7 @@ const reservedDomains = require("../util/reserved-domains.json");
 const domainsPath = path.resolve("domains");
 const files = fs.readdirSync(domainsPath);
 
-const expandReservedDomains = (reserved) => {
+function expandReservedDomains(reserved) {
     const expandedList = [...reserved];
 
     reserved.forEach((item) => {
@@ -58,10 +58,30 @@ const expandReservedDomains = (reserved) => {
     });
 
     return expandedList;
-};
+}
 
 const expandedReservedDomains = expandReservedDomains(reservedDomains);
 
+function findDuplicateKeys(jsonString) {
+    const keyPattern = /"([^"]+)"(?=\s*:)/g;
+    const keys = [];
+    let match;
+
+    // Find all keys in the JSON string
+    while ((match = keyPattern.exec(jsonString)) !== null) {
+        keys.push(match[1]);
+    }
+
+    // Count occurrences of each key
+    const keyCount = {};
+    keys.forEach((key) => {
+        keyCount[key] = (keyCount[key] || 0) + 1;
+    });
+
+    // Return keys that occur more than once
+    return Object.keys(keyCount).filter((key) => keyCount[key] > 1);
+}
+
 function validateFields(t, obj, fields, file, prefix = "") {
     Object.keys(fields).forEach((key) => {
         const fieldPath = prefix ? `${prefix}.${key}` : key;
@@ -109,6 +129,16 @@ t("All files should be valid JSON", (t) => {
     });
 });
 
+t("All files should not have duplicate keys", (t) => {
+    files.forEach((file) => {
+        // Parse JSON as a string because JS automatically gets the last key if there are duplicates
+        const rawData = fs.readFileSync(`${domainsPath}/${file}`, "utf8");
+        const duplicateKeys = findDuplicateKeys(rawData);
+
+        t.true(!duplicateKeys.length, `${file}: Duplicate keys found: ${duplicateKeys.join(", ")}`);
+    });
+});
+
 t("All files should have valid file names", (t) => {
     files.forEach((file) => {
         validateFileName(t, file);
diff --git a/tests/records.test.js b/tests/records.test.js
index a13530cf5..8a1bbabbc 100644
--- a/tests/records.test.js
+++ b/tests/records.test.js
@@ -275,13 +275,3 @@ t("All files should have valid record types", (t) => {
 
     t.pass();
 });
-
-t("All files should not have duplicate record keys", (t) => {
-    files.forEach((file) => {
-        const data = getDomainData(file);
-        const recordKeys = Object.keys(data.record);
-        const uniqueRecordKeys = new Set(recordKeys);
-
-        t.is(recordKeys.length, uniqueRecordKeys.size, `${file}: Duplicate record keys found`);
-    });
-});