diff --git a/server/MetasequoiaImeEngine b/server/MetasequoiaImeEngine
index 76d3c775..12b65317 160000
--- a/server/MetasequoiaImeEngine
+++ b/server/MetasequoiaImeEngine
@@ -1 +1 @@
-Subproject commit 76d3c77546d776a1f04f93f4469667e452a71102
+Subproject commit 12b65317ccd30ae2f074206c197723e6b20e208f
diff --git a/server/tests/src/test_engine_shuangpin_session.cpp b/server/tests/src/test_engine_shuangpin_session.cpp
index 892d93a2..dd02b0b2 100644
--- a/server/tests/src/test_engine_shuangpin_session.cpp
+++ b/server/tests/src/test_engine_shuangpin_session.cpp
@@ -97,6 +97,31 @@ TEST_CASE(EngineShuangpinSessionContinuesCompositionWithSingleHelpcode)
     REQUIRE_EQ(session.get_pinyin_sequence(), std::string("tele"));
 }
 
+TEST_CASE(EngineShuangpinUppercaseSingleHelpcodePrefersSecondCodeMatches)
+{
+    REQUIRE(HelpcodeUtils::select_helpcode_schema("lantian"));
+    EngineInputSession session(SchemeType::Shuangpin);
+    InputLetters(session, "nid");
+    session.reset_state();
+    InputLetters(session, "niD");
+
+    const auto &candidates = session.get_candidates();
+    const auto index_of = [&](const std::string &word) {
+        const auto found = std::find_if(candidates.begin(), candidates.end(),
+                                        [&](const IInputSession::WordItem &item) { return item.word == word; });
+        return static_cast<size_t>(std::distance(candidates.begin(), found));
+    };
+
+    const size_t ni = index_of("泥");
+    const size_t ni_second_code = index_of("溺");
+    const size_t ni_other_second_code = index_of("腻");
+    REQUIRE(ni < candidates.size());
+    REQUIRE(ni_second_code < candidates.size());
+    REQUIRE(ni_other_second_code < candidates.size());
+    REQUIRE(ni_second_code < ni);
+    REQUIRE(ni_other_second_code < ni);
+}
+
 TEST_CASE(EngineShuangpinSessionContinuesCompositionWithDoubleHelpcode)
 {
     EngineInputSession session(SchemeType::Shuangpin);
diff --git a/server/tests/src/test_shuangpin_query.cpp b/server/tests/src/test_shuangpin_query.cpp
index 6e35b5de..6ddea5c9 100644
--- a/server/tests/src/test_shuangpin_query.cpp
+++ b/server/tests/src/test_shuangpin_query.cpp
@@ -12,6 +12,16 @@ TEST_CASE(ApplySegmentationCasesPreservesUppercaseMarkers)
 TEST_CASE(IsFullHelpModeRecognizesDoubleHelpcodePattern)
 {
     REQUIRE(ShuangpinUtil::IsFullHelpMode("xiteleaA"));
+    REQUIRE(ShuangpinUtil::IsFullHelpMode("xiteleAa"));
+    REQUIRE(ShuangpinUtil::IsFullHelpMode("xiteleAA"));
+    REQUIRE(!ShuangpinUtil::IsFullHelpMode("xiteleaa"));
     REQUIRE(!ShuangpinUtil::IsFullHelpMode("xitelea"));
     REQUIRE(!ShuangpinUtil::IsFullHelpMode("xi"));
 }
+
+TEST_CASE(FullHelpCodesUseFirstUppercaseMarkerForReverseOrder)
+{
+    REQUIRE_EQ(ShuangpinUtil::GetFullHelpCodes("xiteleaB"), std::string("ab"));
+    REQUIRE_EQ(ShuangpinUtil::GetFullHelpCodes("xiteleAb"), std::string("ba"));
+    REQUIRE_EQ(ShuangpinUtil::GetFullHelpCodes("xiteleAB"), std::string("ba"));
+}