diff --git a/utils/checkpackagelib/lib_config.py b/utils/checkpackagelib/lib_config.py
index b05831f2c3..f26ca0d898 100644
--- a/utils/checkpackagelib/lib_config.py
+++ b/utils/checkpackagelib/lib_config.py
@@ -233,3 +233,41 @@ class Indent(_CheckFunction):
                 return ["{}:{}: should not be indented"
                         .format(self.filename, lineno),
                         text]
+
+
+class RedefinedConfig(_CheckFunction):
+    CONFIG = re.compile(r"^\s*(menu|)config\s+(BR2_\w+)\b")
+    IF = re.compile(r"^\s*if\s+([^#]*)\b")
+    ENDIF = re.compile(r"^\s*endif\b")
+
+    def before(self):
+        self.configs = {}
+        self.conditional = []
+
+    def check_line(self, lineno, text):
+        if _empty_or_comment(text) or _part_of_help_text(text):
+            return
+
+        m = self.IF.search(text)
+        if m is not None:
+            condition = m.group(1)
+            self.conditional.append(condition)
+            return
+
+        m = self.ENDIF.search(text)
+        if m is not None:
+            self.conditional.pop()
+            return
+
+        m = self.CONFIG.search(text)
+        if m is None:
+            return
+        config = m.group(2)
+
+        key = (config, ' AND '.join(self.conditional))
+        if key in self.configs.keys():
+            previous_line = self.configs[key]
+            return ["{}:{}: config {} redeclared (previous line: {})"
+                    .format(self.filename, lineno, config, previous_line),
+                    text]
+        self.configs[key] = lineno
diff --git a/utils/checkpackagelib/test_lib_config.py b/utils/checkpackagelib/test_lib_config.py
index 91a549adf2..474d17105e 100644
--- a/utils/checkpackagelib/test_lib_config.py
+++ b/utils/checkpackagelib/test_lib_config.py
@@ -385,3 +385,81 @@ Indent = [
 def test_Indent(testname, filename, string, expected):
     warnings = util.check_file(m.Indent, filename, string)
     assert warnings == expected
+
+
+RedefinedConfig = [
+    ('no redefinition',
+     'any',
+     'config BR2_PACKAGE_FOO\n'
+     'bool "foo"\n'
+     'config BR2_PACKAGE_FOO_BAR\n'
+     'bool "foo"\n',
+     []),
+    ('no conditional',
+     'any',
+     'config BR2_PACKAGE_FOO\n'
+     'bool "foo"\n'
+     'config BR2_PACKAGE_BAR\n'
+     'bool "bar"\n'
+     'config BR2_PACKAGE_FOO\n'
+     'bool "foo"\n',
+     [['any:5: config BR2_PACKAGE_FOO redeclared (previous line: 1)',
+       'config BR2_PACKAGE_FOO\n']]),
+    ('three times',
+     'any',
+     'config BR2_PACKAGE_FOO\n'
+     'bool "foo"\n'
+     'config BR2_PACKAGE_FOO\n'
+     'bool "foo"\n'
+     'config BR2_PACKAGE_FOO\n'
+     'bool "foo"\n',
+     [['any:3: config BR2_PACKAGE_FOO redeclared (previous line: 1)',
+       'config BR2_PACKAGE_FOO\n'],
+      ['any:5: config BR2_PACKAGE_FOO redeclared (previous line: 1)',
+       'config BR2_PACKAGE_FOO\n']]),
+    ('same conditional',
+     'any',
+     'if BR2_PACKAGE_BAZ\n'
+     'config BR2_PACKAGE_FOO\n'
+     'bool "foo"\n'
+     'config BR2_PACKAGE_BAR\n'
+     'bool "bar"\n'
+     'config BR2_PACKAGE_FOO\n'
+     'bool "foo"\n'
+     'endif\n',
+     [['any:6: config BR2_PACKAGE_FOO redeclared (previous line: 2)',
+       'config BR2_PACKAGE_FOO\n']]),
+    ('equivalent conditional',
+     'any',
+     'if BR2_PACKAGE_BAZ\n'
+     'config BR2_PACKAGE_FOO\n'
+     'bool "foo"\n'
+     'endif\n'
+     'config BR2_PACKAGE_FOO\n'
+     'bool "foo"\n'
+     'if BR2_PACKAGE_BAZ\n'
+     'config BR2_PACKAGE_FOO\n'
+     'bool "foo"\n'
+     'endif\n',
+     [['any:8: config BR2_PACKAGE_FOO redeclared (previous line: 2)',
+       'config BR2_PACKAGE_FOO\n']]),
+    ('not equivalent conditional',
+     'any',
+     'if BR2_PACKAGE_BAZ\n'
+     'config BR2_PACKAGE_FOO\n'
+     'bool "foo"\n'
+     'endif\n'
+     'config BR2_PACKAGE_FOO\n'
+     'bool "foo"\n'
+     'if !BR2_PACKAGE_BAZ\n'
+     'config BR2_PACKAGE_FOO\n'
+     'bool "foo"\n'
+     'endif\n',
+     []),
+    ]
+
+
+@pytest.mark.parametrize('testname,filename,string,expected', RedefinedConfig)
+def test_RedefinedConfig(testname, filename, string, expected):
+    warnings = util.check_file(m.RedefinedConfig, filename, string)
+    assert warnings == expected