diff --git a/test/intl402/6.2.2_b.js b/test/intl402/6.2.2_b.js
index 17552f207fd2c654958db99570575fd2a389a80f..d9a6d1b24df16e538807e6b966d24563c9229be0 100644
--- a/test/intl402/6.2.2_b.js
+++ b/test/intl402/6.2.2_b.js
@@ -18,7 +18,9 @@ var invalidLanguageTags = [
     "i_klingon",
     "cmn-hans-cn-t-ca-u-ca-x_t-u",
     "enochian_enochian",
-    "de-gregory_u-ca-gregory"
+    "de-gregory_u-ca-gregory",
+    "de-tester-Tester",  // Case-insensitive duplicate variant subtag
+    "de-DE-u-kn-true-U-kn-true",  // Case-insensitive duplicate singleton subtag
 ];
 
 testWithIntlConstructors(function (Constructor) {