diff --git a/spring-context/src/main/java/org/springframework/validation/DataBinder.java b/spring-context/src/main/java/org/springframework/validation/DataBinder.java
index 414bfeb0285..5a453b28545 100644
--- a/spring-context/src/main/java/org/springframework/validation/DataBinder.java
+++ b/spring-context/src/main/java/org/springframework/validation/DataBinder.java
@@ -1069,6 +1069,9 @@ public class DataBinder implements PropertyEditorRegistry, TypeConverter {
 			if (map == null) {
 				map = CollectionFactory.createMap(paramType, 16);
 			}
+			else if (map.containsKey(key)) {
+				continue;
+			}
 
 			String indexedPath = name.substring(0, endIdx + 1);
 			map.put(key, createIndexedValue(paramPath, paramType, elementType, indexedPath, valueResolver));
diff --git a/spring-context/src/test/java/org/springframework/validation/DataBinderConstructTests.java b/spring-context/src/test/java/org/springframework/validation/DataBinderConstructTests.java
index dc4b0d5cb3f..3eac155ad32 100644
--- a/spring-context/src/test/java/org/springframework/validation/DataBinderConstructTests.java
+++ b/spring-context/src/test/java/org/springframework/validation/DataBinderConstructTests.java
@@ -21,6 +21,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Optional;
 import java.util.Set;
+import java.util.concurrent.atomic.AtomicInteger;
 
 import jakarta.validation.constraints.NotNull;
 import org.jspecify.annotations.Nullable;
@@ -158,6 +159,27 @@ class DataBinderConstructTests {
 		assertThat(map.get("c").param1()).isEqualTo("value3");
 	}
 
+	@Test  // gh-37019
+	void dataClassWithMapBindingConstructsValueOncePerKey() {
+		CountingRecord.constructorCallCount.set(0);
+		MapValueResolver valueResolver = new MapValueResolver(Map.of(
+				"countingMap[a].param1", "value1", "countingMap[a].param2", "value2",
+				"countingMap[b].param1", "value3", "countingMap[b].param2", "value4"));
+
+		DataBinder binder = initDataBinder(CountingMapRecord.class);
+		binder.construct(valueResolver);
+
+		CountingMapRecord target = getTarget(binder);
+		Map<String, CountingRecord> map = target.countingMap();
+
+		assertThat(map).hasSize(2);
+		assertThat(map.get("a").param1()).isEqualTo("value1");
+		assertThat(map.get("a").param2()).isEqualTo("value2");
+		assertThat(map.get("b").param1()).isEqualTo("value3");
+		assertThat(map.get("b").param2()).isEqualTo("value4");
+		assertThat(CountingRecord.constructorCallCount).hasValue(2);
+	}
+
 	@Test
 	void dataClassWithArrayBinding() {
 		MapValueResolver valueResolver = new MapValueResolver(Map.of(
@@ -327,6 +349,20 @@ class DataBinderConstructTests {
 	}
 
 
+	record CountingRecord(String param1, String param2) {
+
+		static final AtomicInteger constructorCallCount = new AtomicInteger();
+
+		CountingRecord {
+			constructorCallCount.incrementAndGet();
+		}
+	}
+
+
+	private record CountingMapRecord(Map<String, CountingRecord> countingMap) {
+	}
+
+
 	private record DataClassArrayRecord(DataClass[] dataClassArray) {
 	}