diff --git a/openviking/parse/parsers/markdown.py b/openviking/parse/parsers/markdown.py
index abeb542423..7ded6c1586 100644
--- a/openviking/parse/parsers/markdown.py
+++ b/openviking/parse/parsers/markdown.py
@@ -601,17 +601,22 @@ def _generate_merged_filename(self, sections: List[Tuple[str, str, int]]) -> str
         count = len(names)
         max_len = self.MAX_MERGED_FILENAME_LENGTH
 
+        # Build a content-aware hash from ALL section names AND indices to guarantee
+        # uniqueness even when different merge groups share the same heading names.
+        full_key = "_".join(f"{n}:{i}" for n, _, i in sections)
+        hash_suffix = hashlib.sha256(full_key.encode()).hexdigest()[:8]
+
         if count == 1:
-            name = names[0]
+            base = names[0]
         else:
             suffix = f"_{count}more"
-            max_first_len = max_len - len(suffix)
+            max_first_len = max_len - len(suffix) - 9  # reserve space for _hash
             first_name = names[0][: max(max_first_len, 1)]
-            name = f"{first_name}{suffix}"
+            base = f"{first_name}{suffix}"
+
+        name = f"{base}_{hash_suffix}"
 
         if len(name) > max_len:
-            full_key = "_".join(names)
-            hash_suffix = hashlib.sha256(full_key.encode()).hexdigest()[:8]
             name = f"{name[: max_len - 9]}_{hash_suffix}"
 
         name = name.strip("_")
diff --git a/tests/parse/test_markdown_filename_collision.py b/tests/parse/test_markdown_filename_collision.py
new file mode 100644
index 0000000000..a88651b1f6
--- /dev/null
+++ b/tests/parse/test_markdown_filename_collision.py
@@ -0,0 +1,44 @@
+# Copyright (c) 2026 Beijing Volcano Engine Technology Co., Ltd.
+# SPDX-License-Identifier: Apache-2.0
+"""Tests for _generate_merged_filename uniqueness when headings collide."""
+
+from openviking.parse.parsers.markdown import MarkdownParser
+from openviking_cli.utils.config.parser_config import ParserConfig
+
+
+class TestGenerateMergedFilenameCollision:
+    def _make_parser(self) -> MarkdownParser:
+        return MarkdownParser(ParserConfig())
+
+    def test_duplicate_heading_produces_unique_filenames(self):
+        """Merge groups with same first heading but different content must get unique filenames."""
+        parser = self._make_parser()
+
+        group1 = [
+            ("Our Culture", "content about values", 1),
+            ("Our Culture", "content about mission", 2),
+        ]
+        group2 = [
+            ("Our Culture", "content about team", 3),
+            ("Our Culture", "content about vision", 4),
+        ]
+
+        name1 = parser._generate_merged_filename(group1)
+        name2 = parser._generate_merged_filename(group2)
+
+        assert name1 != name2, f"Filenames must be unique but both are '{name1}'"
+        assert "Our" in name1 or "Culture" in name1  # Still human-readable
+
+    def test_single_section_filename_still_works(self):
+        """Single section should still produce a readable filename."""
+        parser = self._make_parser()
+
+        sections = [("Introduction", "some content", 1)]
+        name = parser._generate_merged_filename(sections)
+
+        assert "Introduction" in name
+
+    def test_empty_sections_returns_merged(self):
+        """Empty sections list should return 'merged'."""
+        parser = self._make_parser()
+        assert parser._generate_merged_filename([]) == "merged"