diff --git a/pipreqs/pipreqs.py b/pipreqs/pipreqs.py
index 0877173..43b737b 100644
--- a/pipreqs/pipreqs.py
+++ b/pipreqs/pipreqs.py
@@ -227,6 +227,29 @@ def output_requirements(imports, symbol):
     generate_requirements_file("-", imports, symbol)
 
 
+def _normalize_package_name(name):
+    return re.sub(r"[-_.]+", "-", name).lower()
+
+
+def _deduplicate_imports(imports):
+    result = []
+    seen = {}
+
+    for item in imports:
+        name = item["name"]
+        key = _normalize_package_name(name)
+        if key in seen:
+            existing = result[seen[key]]
+            if not existing["version"] and item["version"]:
+                result[seen[key]] = item
+            continue
+
+        seen[key] = len(result)
+        result.append(item)
+
+    return result
+
+
 def get_imports_info(imports, pypi_server="https://pypi.python.org/pypi/", proxy=None):
     result = []
 
@@ -584,6 +607,8 @@ def init(args):
         clean(args["--clean"], imports)
         return
 
+    imports = _deduplicate_imports(imports)
+
     if args["--mode"]:
         scheme = args.get("--mode")
         if scheme in ["compat", "gt", "no-pin"]:
diff --git a/tests/test_pipreqs.py b/tests/test_pipreqs.py
index 5e046e0..8bda318 100644
--- a/tests/test_pipreqs.py
+++ b/tests/test_pipreqs.py
@@ -142,6 +142,24 @@ def test_get_pkg_names(self):
         expected_output = ["camel", "Caroline", "Japan", "jury"]
         self.assertEqual(actual_output, expected_output)
 
+    def test_deduplicate_imports_uses_normalized_package_names(self):
+        imports = [
+            {"name": "PyYAML", "version": "6.0.2"},
+            {"name": "pyyaml", "version": "6.0.2"},
+            {"name": "opencv_python", "version": "4.12.0"},
+            {"name": "opencv-python", "version": "4.12.0"},
+            {"name": "example_pkg", "version": None},
+            {"name": "example-pkg", "version": "1.2.3"},
+        ]
+
+        actual_output = pipreqs._deduplicate_imports(imports)
+        expected_output = [
+            {"name": "PyYAML", "version": "6.0.2"},
+            {"name": "opencv_python", "version": "4.12.0"},
+            {"name": "example-pkg", "version": "1.2.3"},
+        ]
+        self.assertEqual(actual_output, expected_output)
+
     def test_get_use_local_only(self):
         """
         Test without checking PyPI, check to see if names of local
@@ -209,6 +227,78 @@ def test_init_local_only(self):
                 item = item.strip().split("==")
                 self.assertTrue(item[0].lower() in self.local)
 
+    @patch("pipreqs.pipreqs.get_all_imports")
+    @patch("pipreqs.pipreqs.get_import_local")
+    def test_init_deduplicates_normalized_requirements(self, get_import_local_mock, get_all_imports_mock):
+        """
+        Test that equivalent package names are only written once.
+        """
+        get_all_imports_mock.return_value = ["yaml", "win32gui"]
+        get_import_local_mock.return_value = [
+            {"name": "PyYAML", "version": "6.0.2", "exports": ["yaml"]},
+            {"name": "pyyaml", "version": "6.0.2", "exports": ["yaml"]},
+            {"name": "pywin32", "version": "310", "exports": ["win32gui"]},
+            {"name": "pywin32", "version": "311", "exports": ["win32gui"]},
+        ]
+
+        pipreqs.init(
+            {
+                "<path>": self.project,
+                "--savepath": None,
+                "--print": False,
+                "--use-local": True,
+                "--force": True,
+                "--proxy": None,
+                "--pypi-server": None,
+                "--diff": None,
+                "--clean": None,
+                "--mode": None,
+            }
+        )
+
+        assert os.path.exists(self.requirements_path) == 1
+        with open(self.requirements_path, "r") as f:
+            data = f.read().splitlines()
+
+        self.assertEqual(["pywin32==310", "PyYAML==6.0.2"], data)
+
+    @patch("pipreqs.pipreqs.get_all_imports")
+    @patch("pipreqs.pipreqs.get_import_local")
+    def test_init_clean_keeps_normalized_alias_requirements(
+        self, get_import_local_mock, get_all_imports_mock
+    ):
+        """
+        Test that --clean keeps raw requirement names before output deduplication.
+        """
+        get_all_imports_mock.return_value = ["cv2"]
+        get_import_local_mock.return_value = [
+            {"name": "opencv-python", "version": "4.12.0", "exports": ["cv2"]},
+            {"name": "opencv_python", "version": "4.12.0", "exports": ["cv2"]},
+        ]
+        with open(self.requirements_path, "w") as f:
+            f.write("opencv_python==4.12.0\nunused-package==1.0.0\n")
+
+        pipreqs.init(
+            {
+                "<path>": self.project,
+                "--savepath": None,
+                "--print": False,
+                "--use-local": True,
+                "--force": True,
+                "--proxy": None,
+                "--pypi-server": None,
+                "--diff": None,
+                "--clean": self.requirements_path,
+                "--mode": None,
+            }
+        )
+
+        with open(self.requirements_path, "r") as f:
+            data = f.read()
+
+        self.assertIn("opencv_python==4.12.0", data)
+        self.assertNotIn("unused-package", data)
+
     def test_init_savepath(self):
         """
         Test that we can save requirements.txt correctly