diff --git a/CHANGELOG.md b/CHANGELOG.md
index fc05d65..c6a0fd6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,25 +2,21 @@
 
 ## v0.1.1
 
-```
-## v0.1.1
-
 ✨ Added
 - Added git hooks management and auto-fix on pre-commit
 - Added git hooks management CLI
-- Added emoji option to CLI and config to control emoji prefixes
+- Added emoji option to cli and config to control emoji prefixes
+
+🔄 Changed
+- Improved changelog generation to handle existing files and duplicate headers
+
+🗑️ Removed
+- Removed duplicate changelog entries
 
 📝 Documentation
+- Updated changelog for v0.1.1 release
 - Recommended installation using pipx and uv
 
-🔧 Maintenance
-- Removed duplicate changelog entries
-- Updated changelog for v0.1.1 release
-```
-
-## v0.1.0
-
-```
 ## v0.1.0
 
 ✨ Added
@@ -29,7 +25,6 @@
 - ✨ docs(changelog): Add ChangelogGenerator class documentation
 - 🐛 docs(changelog): Updated changelog format and added ChangelogGenerator class documentation
 
-
 🔄 Changed
 - Changes for version 0.1.0:
 - Updated commit message and changelog generation using AI 👨‍💻
@@ -43,7 +38,4 @@
 - 📚 Update `LICENSE`
 
 🗑️ Removed
-- Removed unused variable in `_run_git_command` calls 🗑️
-
-
-```
\ No newline at end of file
+- Removed unused variable in `_run_git_command` calls 🗑️
\ No newline at end of file
diff --git a/devtools/changelog/generator.py b/devtools/changelog/generator.py
index b23b642..3a98ca6 100644
--- a/devtools/changelog/generator.py
+++ b/devtools/changelog/generator.py
@@ -91,9 +91,28 @@ class ChangelogGenerator(AIService):
             version
         } with these changes:\n\n{changes_text}"
 
-        return self.generate_completion(
+        raw = self.generate_completion(
             system_prompt, user_prompt, temperature=temperature
         )
+        return self._clean_changelog_content(raw, version)
+
+    def _clean_changelog_content(self, text: str, version: str) -> str:
+        """Sanitize AI output to avoid nested headers and code fences.
+
+        - Remove triple backtick fences
+        - Remove duplicate version headers inside content (e.g., '## v1.2.3')
+        - Trim excess surrounding whitespace
+        """
+        cleaned = text.replace("```", "").strip()
+        # Drop any inner version headers
+        normalized_version = version.lstrip("vV")
+        inner_header_pattern = rf"^##\s+v?{re.escape(normalized_version)}\s*$"
+        lines = []
+        for line in cleaned.splitlines():
+            if re.match(inner_header_pattern, line.strip()):
+                continue
+            lines.append(line)
+        return "\n".join(lines).strip()
 
     def update_changelog_file(
         self,