diff --git a/spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/environment/NativeEnvironmentRepository.java b/spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/environment/NativeEnvironmentRepository.java
index 1df63fc8..14ad7464 100644
--- a/spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/environment/NativeEnvironmentRepository.java
+++ b/spring-cloud-config-server/src/main/java/org/springframework/cloud/config/server/environment/NativeEnvironmentRepository.java
@@ -221,7 +221,8 @@ public class NativeEnvironmentRepository implements EnvironmentRepository, Searc
 		Environment result = new Environment(value.getName(), value.getProfiles(), value.getLabel(), this.version,
 				value.getState());
 		for (PropertySource source : value.getPropertySources()) {
-			String name = source.getName();
+			String originalName = source.getName();
+			String name = originalName;
 			if (this.environment.getPropertySources().contains(name)) {
 				continue;
 			}
@@ -271,13 +272,20 @@ public class NativeEnvironmentRepository implements EnvironmentRepository, Searc
 				if (!matches) {
 					// Don't include this one: it wasn't matched by our search locations
 					if (logger.isDebugEnabled()) {
-						logger.debug("Not adding property source: " + name);
+						logger.debug("Not adding property source: " + originalName);
 					}
 					continue;
 				}
 			}
-			logger.info("Adding property source: " + name);
-			result.add(new PropertySource(name, source.getSource()));
+			logger.info("Adding property source: " + originalName);
+			if (originalName.contains("document #")) {
+				// this is a multi-document file, use originalName for uniqueness.
+				result.add(new PropertySource(originalName, source.getSource()));
+			}
+			else {
+				// many other file tests rely on the mangled name
+				result.add(new PropertySource(name, source.getSource()));
+			}
 		}
 		return result;
 	}
diff --git a/spring-cloud-config-server/src/test/java/org/springframework/cloud/config/server/environment/NativeEnvironmentRepositoryTests.java b/spring-cloud-config-server/src/test/java/org/springframework/cloud/config/server/environment/NativeEnvironmentRepositoryTests.java
index 60f094d6..99bd964a 100644
--- a/spring-cloud-config-server/src/test/java/org/springframework/cloud/config/server/environment/NativeEnvironmentRepositoryTests.java
+++ b/spring-cloud-config-server/src/test/java/org/springframework/cloud/config/server/environment/NativeEnvironmentRepositoryTests.java
@@ -82,6 +82,31 @@ public class NativeEnvironmentRepositoryTests {
 		Environment environment = this.repository.findOne("foo", "development", "master");
 		assertThat(environment.getPropertySources().size()).isEqualTo(2);
 		assertThat(environment.getVersion()).as("version was wrong").isEqualTo("myversion");
+		// gh-1778 property sources has the same name.
+		assertThat(environment.getPropertySources().get(0).getName())
+				.isNotEqualTo(environment.getPropertySources().get(1).getName());
+	}
+
+	@Test
+	public void prefixedYaml() {
+		this.repository.setSearchLocations("classpath:/test");
+		Environment environment = this.repository.findOne("bar", "development", "master");
+		assertThat(environment.getPropertySources().size()).isEqualTo(2);
+		assertThat(environment.getVersion()).as("version was wrong").isEqualTo("myversion");
+		// gh-1778 property sources has the same name.
+		assertThat(environment.getPropertySources().get(0).getName())
+				.isNotEqualTo(environment.getPropertySources().get(1).getName());
+	}
+
+	@Test
+	public void prefixedMultiDocProperties() {
+		this.repository.setSearchLocations("classpath:/test");
+		Environment environment = this.repository.findOne("baz", "development", "master");
+		assertThat(environment.getPropertySources().size()).isEqualTo(2);
+		assertThat(environment.getVersion()).as("version was wrong").isEqualTo("myversion");
+		// gh-1778 property sources has the same name.
+		assertThat(environment.getPropertySources().get(0).getName())
+				.isNotEqualTo(environment.getPropertySources().get(1).getName());
 	}
 
 	@Test
diff --git a/spring-cloud-config-server/src/test/resources/test/bar.yml b/spring-cloud-config-server/src/test/resources/test/bar.yml
new file mode 100644
index 00000000..688e1d94
--- /dev/null
+++ b/spring-cloud-config-server/src/test/resources/test/bar.yml
@@ -0,0 +1,12 @@
+client:
+  test: Default
+
+---
+
+spring:
+  config:
+    activate:
+      on-profile: development
+
+client:
+  test: Development
diff --git a/spring-cloud-config-server/src/test/resources/test/baz.properties b/spring-cloud-config-server/src/test/resources/test/baz.properties
new file mode 100644
index 00000000..66233c56
--- /dev/null
+++ b/spring-cloud-config-server/src/test/resources/test/baz.properties
@@ -0,0 +1,5 @@
+client.test=Default
+
+#---
+spring.config.activate.on-profile=development
+client.test=Development