diff --git a/claude-code-enforcer/src/main/java/io/github/adamw7/tools/enforcer/doc/DocumentConsistency.java b/claude-code-enforcer/src/main/java/io/github/adamw7/tools/enforcer/doc/DocumentConsistency.java
index 719776a5..391e6729 100644
--- a/claude-code-enforcer/src/main/java/io/github/adamw7/tools/enforcer/doc/DocumentConsistency.java
+++ b/claude-code-enforcer/src/main/java/io/github/adamw7/tools/enforcer/doc/DocumentConsistency.java
@@ -104,6 +104,6 @@ private String describe(Document document, Optional<String> value) {
 
 	private Optional<String> capture(Pattern pattern, String content) {
 		Matcher matcher = pattern.matcher(content);
-		return matcher.find() ? Optional.of(matcher.group(1)) : Optional.empty();
+		return matcher.find() ? Optional.ofNullable(matcher.group(1)) : Optional.empty();
 	}
 }
diff --git a/claude-code-enforcer/src/main/java/io/github/adamw7/tools/enforcer/text/MarkdownDocument.java b/claude-code-enforcer/src/main/java/io/github/adamw7/tools/enforcer/text/MarkdownDocument.java
index 11a07a2f..0abd93b1 100644
--- a/claude-code-enforcer/src/main/java/io/github/adamw7/tools/enforcer/text/MarkdownDocument.java
+++ b/claude-code-enforcer/src/main/java/io/github/adamw7/tools/enforcer/text/MarkdownDocument.java
@@ -95,7 +95,13 @@ public boolean hasBody(String heading) {
 		return index >= 0 && hasBodyAt(index);
 	}
 
-	/** The headings from {@code wanted} that are present, in the order they appear in the document. */
+	/**
+	 * The headings from {@code wanted} that are present, in the order they first
+	 * appear in the document, each listed once. A required heading that appears
+	 * more than once is reported by its first occurrence, so the order comparison
+	 * matches the de-duplicated set of present sections rather than reporting a
+	 * spurious out-of-order failure.
+	 */
 	public List<String> headingsInOrder(List<String> wanted) {
 		Set<String> required = new LinkedHashSet<>(wanted);
 		List<String> ordered = new ArrayList<>();
@@ -106,7 +112,7 @@ public List<String> headingsInOrder(List<String> wanted) {
 	}
 
 	private void addIfRequiredHeading(String line, boolean lineInsideFence, Set<String> required, List<String> ordered) {
-		if (!lineInsideFence && required.contains(line)) {
+		if (!lineInsideFence && required.remove(line)) {
 			ordered.add(line);
 		}
 	}
diff --git a/claude-code-enforcer/src/test/java/io/github/adamw7/tools/enforcer/doc/ClaudeMdFormatRuleTest.java b/claude-code-enforcer/src/test/java/io/github/adamw7/tools/enforcer/doc/ClaudeMdFormatRuleTest.java
index c4fb311e..feb0b8af 100644
--- a/claude-code-enforcer/src/test/java/io/github/adamw7/tools/enforcer/doc/ClaudeMdFormatRuleTest.java
+++ b/claude-code-enforcer/src/test/java/io/github/adamw7/tools/enforcer/doc/ClaudeMdFormatRuleTest.java
@@ -271,6 +271,20 @@ void failsWhenRequiredSectionsAppearInTheWrongOrder() {
 		assertTrue(exception.getMessage().contains("out of order"), exception.getMessage());
 	}
 
+	@Test
+	void doesNotReportOutOfOrderWhenARequiredSectionAppearsTwice() {
+		String duplicated = VALID_CONTENT + """
+				## Testing
+				More notes on testing.
+				""";
+		ClaudeMdFormatRule rule = ruleFor(duplicated);
+		rule.setEnforceSectionOrder(true);
+
+		// The sections are in the configured order; a repeated "## Testing" must be
+		// counted once by its first occurrence, not flagged as out of order.
+		assertDoesNotThrow(rule::execute);
+	}
+
 	@Test
 	void failsWhenALineExceedsTheMaximumLength() {
 		ClaudeMdFormatRule rule = ruleFor(VALID_CONTENT + "\n" + "x".repeat(200) + "\n");
diff --git a/claude-code-enforcer/src/test/java/io/github/adamw7/tools/enforcer/doc/CrossDocConsistencyRuleTest.java b/claude-code-enforcer/src/test/java/io/github/adamw7/tools/enforcer/doc/CrossDocConsistencyRuleTest.java
index 65f26ade..3a378ba3 100644
--- a/claude-code-enforcer/src/test/java/io/github/adamw7/tools/enforcer/doc/CrossDocConsistencyRuleTest.java
+++ b/claude-code-enforcer/src/test/java/io/github/adamw7/tools/enforcer/doc/CrossDocConsistencyRuleTest.java
@@ -68,6 +68,17 @@ void failsWithAClearMessageWhenAPatternHasNoCapturingGroup() {
 		assertTrue(exception.getMessage().contains("must declare a capturing group"), exception.getMessage());
 	}
 
+	@Test
+	void treatsANonParticipatingOptionalGroupAsAbsent() {
+		CrossDocConsistencyRule rule = ruleFor("Uses proto3 here.", "No proto mentioned.");
+		rule.setConsistentPatterns(List.of("proto(\\d)?"));
+
+		// The group is optional, so a bare "proto" match captures null. That must be
+		// treated as a mismatch against the concrete "3", not throw a NullPointerException.
+		EnforcerRuleException exception = assertThrows(EnforcerRuleException.class, rule::execute);
+		assertTrue(exception.getMessage().contains("'3'"), exception.getMessage());
+	}
+
 	@Test
 	void failsWhenAFileIsMissing() {
 		CrossDocConsistencyRule rule = new CrossDocConsistencyRule();