diff --git a/persistence-service-v1/persistence-service-external-api-impl-v1/src/main/java/com/iqser/red/persistence/service/v1/external/api/impl/controller/DossierController.java b/persistence-service-v1/persistence-service-external-api-impl-v1/src/main/java/com/iqser/red/persistence/service/v1/external/api/impl/controller/DossierController.java
index f3d31656c..9ef7fb81a 100644
--- a/persistence-service-v1/persistence-service-external-api-impl-v1/src/main/java/com/iqser/red/persistence/service/v1/external/api/impl/controller/DossierController.java
+++ b/persistence-service-v1/persistence-service-external-api-impl-v1/src/main/java/com/iqser/red/persistence/service/v1/external/api/impl/controller/DossierController.java
@@ -10,13 +10,13 @@ import java.time.OffsetDateTime;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
 import java.util.TreeSet;
 import java.util.stream.Collectors;
-import java.util.stream.Stream;
 
 import org.apache.commons.lang3.StringUtils;
 import org.springframework.http.HttpHeaders;
@@ -33,17 +33,16 @@ import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
 
 import com.google.common.collect.Lists;
-import com.iqser.red.service.persistence.management.v1.processor.service.users.model.User;
-import com.knecon.fforesight.keycloakcommons.security.KeycloakSecurity;
-import com.iqser.red.service.persistence.management.v1.processor.roles.ApplicationRoles;
 import com.iqser.red.service.persistence.management.v1.processor.acl.custom.dossier.DossierACLService;
 import com.iqser.red.service.persistence.management.v1.processor.exception.BadRequestException;
+import com.iqser.red.service.persistence.management.v1.processor.roles.ApplicationRoles;
 import com.iqser.red.service.persistence.management.v1.processor.service.AccessControlService;
 import com.iqser.red.service.persistence.management.v1.processor.service.DossierManagementService;
 import com.iqser.red.service.persistence.management.v1.processor.service.FileStatusManagementService;
-import com.iqser.red.service.persistence.management.v1.processor.service.users.UserService;
 import com.iqser.red.service.persistence.management.v1.processor.service.persistence.AuditPersistenceService;
 import com.iqser.red.service.persistence.management.v1.processor.service.persistence.NotificationPersistenceService;
+import com.iqser.red.service.persistence.management.v1.processor.service.users.UserService;
+import com.iqser.red.service.persistence.management.v1.processor.service.users.model.User;
 import com.iqser.red.service.persistence.service.v1.api.external.resource.DossierResource;
 import com.iqser.red.service.persistence.service.v1.api.shared.model.AuditCategory;
 import com.iqser.red.service.persistence.service.v1.api.shared.model.DossierChangeEntry;
@@ -55,6 +54,7 @@ import com.iqser.red.service.persistence.service.v1.api.shared.model.common.JSON
 import com.iqser.red.service.persistence.service.v1.api.shared.model.dossiertemplate.dossier.CreateOrUpdateDossierRequest;
 import com.iqser.red.service.persistence.service.v1.api.shared.model.dossiertemplate.dossier.Dossier;
 import com.iqser.red.service.persistence.service.v1.api.shared.model.notification.NotificationType;
+import com.knecon.fforesight.keycloakcommons.security.KeycloakSecurity;
 
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
@@ -167,7 +167,10 @@ public class DossierController implements DossierResource {
                 }
             }
 
-            Stream.concat(members.stream(), approvers.stream())
+            Set<String> uniqueMembers = new LinkedHashSet<>(members);
+            uniqueMembers.addAll(approvers);
+
+            uniqueMembers.stream()
                     .filter(member -> !member.equals(ownerId) && !member.equals(KeycloakSecurity.getUserId()) && (existingDossier.getMemberIds() == null || !existingDossier.getMemberIds()
                             .contains(member)))
                     .forEach(member -> notificationPersistenceService.insertNotification(AddNotificationRequest.builder()
diff --git a/persistence-service-v1/persistence-service-external-api-v1/src/main/java/com/iqser/red/service/persistence/service/v1/api/external/resource/NotificationResource.java b/persistence-service-v1/persistence-service-external-api-v1/src/main/java/com/iqser/red/service/persistence/service/v1/api/external/resource/NotificationResource.java
index f689e8ae5..96dd3896f 100644
--- a/persistence-service-v1/persistence-service-external-api-v1/src/main/java/com/iqser/red/service/persistence/service/v1/api/external/resource/NotificationResource.java
+++ b/persistence-service-v1/persistence-service-external-api-v1/src/main/java/com/iqser/red/service/persistence/service/v1/api/external/resource/NotificationResource.java
@@ -42,7 +42,6 @@ public interface NotificationResource {
     @ResponseStatus(value = HttpStatus.NO_CONTENT)
     @Operation(summary = "Mark a notifications as seen or unseen", description = "None")
     @ApiResponses(value = {@ApiResponse(responseCode = "204", description = "OK")})
-
     @PostMapping(value = NOTIFICATION_PATH + TOGGLE_SEEN_PATH, consumes = MediaType.APPLICATION_JSON_VALUE)
     void toggleNotificationSeen(@RequestBody List<String> notificationIds, @RequestParam(SET_SEEN_PARAM) boolean setSeen);