diff --git a/src/main/java/org/springframework/data/mapping/model/ClassGeneratingPropertyAccessorFactory.java b/src/main/java/org/springframework/data/mapping/model/ClassGeneratingPropertyAccessorFactory.java
index 5396f59ae..29064788b 100644
--- a/src/main/java/org/springframework/data/mapping/model/ClassGeneratingPropertyAccessorFactory.java
+++ b/src/main/java/org/springframework/data/mapping/model/ClassGeneratingPropertyAccessorFactory.java
@@ -317,13 +317,26 @@ public class ClassGeneratingPropertyAccessorFactory implements PersistentPropert
 		static Class<?> generateCustomAccessorClass(PersistentEntity<?, ?> entity) {
 
 			String className = generateClassName(entity);
-			byte[] bytecode = generateBytecode(className.replace('.', '/'), entity);
 			Class<?> type = entity.getType();
+			ClassLoader classLoader = type.getClassLoader();
+
+			if (ClassUtils.isPresent(className, classLoader)) {
+
+				try {
+					return ClassUtils.forName(className, classLoader);
+				} catch (Exception o_O) {
+					throw new IllegalStateException(o_O);
+				}
+			}
+
+			byte[] bytecode = generateBytecode(className.replace('.', '/'), entity);
 
 			try {
-				return ReflectUtils.defineClass(className, bytecode, type.getClassLoader(), type.getProtectionDomain(), type);
-			} catch (Exception e) {
-				throw new IllegalStateException(e);
+
+				return ReflectUtils.defineClass(className, bytecode, classLoader, type.getProtectionDomain(), type);
+
+			} catch (Exception o_O) {
+				throw new IllegalStateException(o_O);
 			}
 		}
 
diff --git a/src/test/java/org/springframework/data/mapping/model/PropertyAccessorClassGeneratorUnitTests.java b/src/test/java/org/springframework/data/mapping/model/PropertyAccessorClassGeneratorUnitTests.java
new file mode 100644
index 000000000..1ccad740b
--- /dev/null
+++ b/src/test/java/org/springframework/data/mapping/model/PropertyAccessorClassGeneratorUnitTests.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright 2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.mapping.model;
+
+import static org.assertj.core.api.Assertions.*;
+
+import org.junit.Test;
+import org.springframework.data.mapping.PersistentEntity;
+import org.springframework.data.mapping.context.SampleMappingContext;
+import org.springframework.data.mapping.context.SamplePersistentProperty;
+import org.springframework.data.mapping.model.ClassGeneratingPropertyAccessorFactory.PropertyAccessorClassGenerator;
+
+/**
+ * Unit tests for {@link PropertyAccessorClassGeneratorUnitTests}.
+ *
+ * @author Oliver Drotbohm
+ */
+public class PropertyAccessorClassGeneratorUnitTests {
+
+	@Test // DATACMNS-1602
+	public void reusesAlreadyDeclaredClass() {
+
+		SampleMappingContext context = new SampleMappingContext();
+		PersistentEntity<Object, SamplePersistentProperty> entity = context.getRequiredPersistentEntity(Sample.class);
+
+		PropertyAccessorClassGenerator.generateCustomAccessorClass(entity);
+
+		assertThatCode(() -> PropertyAccessorClassGenerator.generateCustomAccessorClass(entity)) //
+				.doesNotThrowAnyException();
+	}
+
+	static class Sample {}
+}