diff --git a/vector-stores/spring-ai-pgvector-store/src/main/java/org/springframework/ai/vectorstore/pgvector/PgVectorStore.java b/vector-stores/spring-ai-pgvector-store/src/main/java/org/springframework/ai/vectorstore/pgvector/PgVectorStore.java
index ffccfb353e..abcd200d2d 100644
--- a/vector-stores/spring-ai-pgvector-store/src/main/java/org/springframework/ai/vectorstore/pgvector/PgVectorStore.java
+++ b/vector-stores/spring-ai-pgvector-store/src/main/java/org/springframework/ai/vectorstore/pgvector/PgVectorStore.java
@@ -635,7 +635,13 @@ public Document mapRow(ResultSet rs, int rowNum) throws SQLException {
 			Float distance = rs.getFloat(COLUMN_DISTANCE);
 
 			Map<String, Object> metadata = toMap(pgMetadata);
-			metadata.put(DocumentMetadata.DISTANCE.value(), distance);
+			if (metadata.containsKey(DocumentMetadata.DISTANCE.value())) {
+				logger.warn("Skipping computed similarity distance for document " + id
+						+ " because its metadata already contains a '" + DocumentMetadata.DISTANCE.value() + "' key");
+			}
+			else {
+				metadata.put(DocumentMetadata.DISTANCE.value(), distance);
+			}
 
 			// @formatter:off
 			return Document.builder()
diff --git a/vector-stores/spring-ai-pgvector-store/src/test/java/org/springframework/ai/vectorstore/pgvector/PgVectorStoreTests.java b/vector-stores/spring-ai-pgvector-store/src/test/java/org/springframework/ai/vectorstore/pgvector/PgVectorStoreTests.java
index 8cf4c3990e..43a54a6a2f 100644
--- a/vector-stores/spring-ai-pgvector-store/src/test/java/org/springframework/ai/vectorstore/pgvector/PgVectorStoreTests.java
+++ b/vector-stores/spring-ai-pgvector-store/src/test/java/org/springframework/ai/vectorstore/pgvector/PgVectorStoreTests.java
@@ -16,6 +16,7 @@
 
 package org.springframework.ai.vectorstore.pgvector;
 
+import java.sql.ResultSet;
 import java.util.Collections;
 import java.util.List;
 
@@ -24,8 +25,10 @@
 import org.junit.jupiter.params.provider.CsvSource;
 import org.mockito.ArgumentCaptor;
 import org.mockito.ArgumentMatchers;
+import org.postgresql.util.PGobject;
 
 import org.springframework.ai.document.Document;
+import org.springframework.ai.document.DocumentMetadata;
 import org.springframework.ai.embedding.EmbeddingModel;
 import org.springframework.ai.vectorstore.SearchRequest;
 import org.springframework.ai.vectorstore.filter.Filter;
@@ -206,4 +209,59 @@ void similaritySearchDoublesSingleQuotesInsideJsonPathSqlLiteral() {
 		assertThat(sqlCaptor.getValue()).contains("O''Brien");
 	}
 
+	@Test
+	@SuppressWarnings("unchecked")
+	void rowMapperSkipsDistanceMetadataWhenUserAlreadyUsesThatKey() throws Exception {
+		var jdbcTemplate = mock(JdbcTemplate.class);
+		var embeddingModel = mock(EmbeddingModel.class);
+		ArgumentCaptor<RowMapper<Document>> rowMapperCaptor = ArgumentCaptor.forClass(RowMapper.class);
+		when(jdbcTemplate.query(anyString(), rowMapperCaptor.capture(), any(), any(), any(), any()))
+			.thenReturn(List.of());
+
+		var store = PgVectorStore.builder(jdbcTemplate, embeddingModel).build();
+		store.doSimilaritySearch(SearchRequest.builder().query("hello").topK(5).similarityThresholdAll().build());
+
+		var pgMetadata = new PGobject();
+		pgMetadata.setType("json");
+		pgMetadata.setValue("{\"distance\": \"12.5 miles from depot\"}");
+
+		var resultSet = mock(ResultSet.class);
+		when(resultSet.getString("id")).thenReturn("doc-1");
+		when(resultSet.getString("content")).thenReturn("hello world");
+		when(resultSet.getObject("metadata", PGobject.class)).thenReturn(pgMetadata);
+		when(resultSet.getFloat("distance")).thenReturn(0.42f);
+
+		Document document = rowMapperCaptor.getValue().mapRow(resultSet, 0);
+
+		assertThat(document.getMetadata()).containsEntry(DocumentMetadata.DISTANCE.value(), "12.5 miles from depot");
+		assertThat(document.getScore()).isEqualTo(1.0 - 0.42f);
+	}
+
+	@Test
+	@SuppressWarnings("unchecked")
+	void rowMapperAddsDistanceMetadataWhenAbsent() throws Exception {
+		var jdbcTemplate = mock(JdbcTemplate.class);
+		var embeddingModel = mock(EmbeddingModel.class);
+		ArgumentCaptor<RowMapper<Document>> rowMapperCaptor = ArgumentCaptor.forClass(RowMapper.class);
+		when(jdbcTemplate.query(anyString(), rowMapperCaptor.capture(), any(), any(), any(), any()))
+			.thenReturn(List.of());
+
+		var store = PgVectorStore.builder(jdbcTemplate, embeddingModel).build();
+		store.doSimilaritySearch(SearchRequest.builder().query("hello").topK(5).similarityThresholdAll().build());
+
+		var pgMetadata = new PGobject();
+		pgMetadata.setType("json");
+		pgMetadata.setValue("{\"author\": \"jane\"}");
+
+		var resultSet = mock(ResultSet.class);
+		when(resultSet.getString("id")).thenReturn("doc-1");
+		when(resultSet.getString("content")).thenReturn("hello world");
+		when(resultSet.getObject("metadata", PGobject.class)).thenReturn(pgMetadata);
+		when(resultSet.getFloat("distance")).thenReturn(0.42f);
+
+		Document document = rowMapperCaptor.getValue().mapRow(resultSet, 0);
+
+		assertThat(document.getMetadata()).containsEntry(DocumentMetadata.DISTANCE.value(), 0.42f);
+	}
+
 }