diff --git a/mvc/src/test/java/duplicate/case1/TestController.java b/mvc/src/test/java/duplicate/case1/TestController.java
new file mode 100644
index 0000000000..ab89f06ea7
--- /dev/null
+++ b/mvc/src/test/java/duplicate/case1/TestController.java
@@ -0,0 +1,22 @@
+package duplicate.case1;
+
+import context.org.springframework.stereotype.Controller;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import web.org.springframework.web.bind.annotation.RequestMapping;
+import web.org.springframework.web.bind.annotation.RequestMethod;
+import webmvc.org.springframework.web.servlet.ModelAndView;
+
+@Controller
+public class TestController {
+
+    private static final Logger log = LoggerFactory.getLogger(samples.TestController.class);
+
+    @RequestMapping(value = "/get-test", method = RequestMethod.GET)
+    public ModelAndView duplicatedMethod(final HttpServletRequest request,
+                                   final HttpServletResponse response) {
+        return null;
+    }
+}
diff --git a/mvc/src/test/java/duplicate/case2/TestController.java b/mvc/src/test/java/duplicate/case2/TestController.java
new file mode 100644
index 0000000000..0e56116850
--- /dev/null
+++ b/mvc/src/test/java/duplicate/case2/TestController.java
@@ -0,0 +1,28 @@
+package duplicate.case2;
+
+import context.org.springframework.stereotype.Controller;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import web.org.springframework.web.bind.annotation.RequestMapping;
+import web.org.springframework.web.bind.annotation.RequestMethod;
+import webmvc.org.springframework.web.servlet.ModelAndView;
+
+@Controller
+public class TestController {
+
+    private static final Logger log = LoggerFactory.getLogger(samples.TestController.class);
+
+    @RequestMapping(value = "/get-test", method = RequestMethod.GET)
+    public ModelAndView duplicatedMethod1(final HttpServletRequest request,
+                                         final HttpServletResponse response) {
+        return null;
+    }
+
+    @RequestMapping(value = "/get-test", method = RequestMethod.GET)
+    public ModelAndView duplicatedMethod2(final HttpServletRequest request,
+                                         final HttpServletResponse response) {
+        return null;
+    }
+}
diff --git a/mvc/src/test/java/webmvc/org/springframework/web/servlet/mvc/tobe/AnnotationHandlerMappingTest.java b/mvc/src/test/java/webmvc/org/springframework/web/servlet/mvc/tobe/AnnotationHandlerMappingTest.java
index dcec215a3f..494f21936f 100644
--- a/mvc/src/test/java/webmvc/org/springframework/web/servlet/mvc/tobe/AnnotationHandlerMappingTest.java
+++ b/mvc/src/test/java/webmvc/org/springframework/web/servlet/mvc/tobe/AnnotationHandlerMappingTest.java
@@ -6,6 +6,7 @@
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
@@ -19,6 +20,27 @@ void setUp() {
         handlerMapping.initialize();
     }
 
+    @Test
+    void methodDuplicationException_case1() {
+        // given & when & then
+        AnnotationHandlerMapping duplicatedHandlerMapping = new AnnotationHandlerMapping(
+            "samples",
+            "duplicate.case1");
+        assertThatThrownBy(() -> duplicatedHandlerMapping.initialize())
+            .isInstanceOf(IllegalArgumentException.class)
+            .hasMessage("Duplicated HandlerKey");
+    }
+
+    @Test
+    void methodDuplicationException_case2() {
+        // given & when & then
+        AnnotationHandlerMapping duplicatedHandlerMapping = new AnnotationHandlerMapping(
+            "duplicate.case2");
+        assertThatThrownBy(() -> duplicatedHandlerMapping.initialize())
+            .isInstanceOf(IllegalArgumentException.class)
+            .hasMessage("Duplicated HandlerKey");
+    }
+
     @Test
     void get() throws Exception {
         final var request = mock(HttpServletRequest.class);