diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/orders/OrderCRUDController.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/orders/OrderCRUDController.java
index d68d09454..3ee45c223 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/orders/OrderCRUDController.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/orders/OrderCRUDController.java
@@ -246,6 +246,7 @@ public class OrderCRUDController extends GenericForwardComposer {
             .getFellowIfAny("orderElementAuthorizations");
         orderAuthorizationController = (OrderAuthorizationController) orderElementAuthorizations
             .getVariable("orderAuthorizationController", true);
+        orderAuthorizationController.setMessagesForUserComponent(messagesForUser);
     }
 
     public List<Order> getOrders() {
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/users/OrderAuthorizationController.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/users/OrderAuthorizationController.java
index 2983bf428..0f9e22a80 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/users/OrderAuthorizationController.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/users/OrderAuthorizationController.java
@@ -20,6 +20,8 @@
 
 package org.navalplanner.web.users;
 
+import static org.navalplanner.web.I18nHelper._;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -30,6 +32,8 @@ import org.navalplanner.business.users.entities.Profile;
 import org.navalplanner.business.users.entities.ProfileOrderAuthorization;
 import org.navalplanner.business.users.entities.User;
 import org.navalplanner.business.users.entities.UserOrderAuthorization;
+import org.navalplanner.web.common.IMessagesForUser;
+import org.navalplanner.web.common.Level;
 import org.navalplanner.web.common.Util;
 import org.zkoss.zk.ui.Component;
 import org.zkoss.zk.ui.util.GenericForwardComposer;
@@ -47,6 +51,8 @@ public class OrderAuthorizationController extends GenericForwardComposer{
 
     private IOrderAuthorizationModel orderAuthorizationModel;
 
+    private IMessagesForUser messagesForUser;
+
     @Override
     public void doAfterCompose(Component comp) throws Exception {
         super.doAfterCompose(comp);
@@ -88,12 +94,26 @@ public class OrderAuthorizationController extends GenericForwardComposer{
                 authorizations.add(OrderAuthorizationType.WRITE_AUTHORIZATION);
             }
             if (comboItem.getValue() instanceof User) {
-                orderAuthorizationModel.addUserOrderAuthorization(
-                        (User)comboItem.getValue(), authorizations);
+                List<OrderAuthorizationType> result =
+                    orderAuthorizationModel.addUserOrderAuthorization(
+                            (User)comboItem.getValue(), authorizations);
+                if(result != null) {
+                    messagesForUser.showMessage(Level.WARNING,
+                            _("Cannot add some authorizations for user {0}. " +
+                                    "Probably they are already present.",
+                                    ((User)comboItem.getValue()).getLoginName()));
+                }
             }
             else if (comboItem.getValue() instanceof Profile) {
-                orderAuthorizationModel.addProfileOrderAuthorization(
-                        (Profile)comboItem.getValue(), authorizations);
+                List<OrderAuthorizationType> result =
+                    orderAuthorizationModel.addProfileOrderAuthorization(
+                            (Profile)comboItem.getValue(), authorizations);
+                if(result != null) {
+                    messagesForUser.showMessage(Level.WARNING,
+                            _("Cannot add some authorizations for profile {0}. " +
+                                    "Probably they are already present.",
+                                    ((Profile)comboItem.getValue()).getProfileName()));
+                }
             }
         }
         Util.reloadBindings(window);
@@ -103,4 +123,8 @@ public class OrderAuthorizationController extends GenericForwardComposer{
         orderAuthorizationModel.removeOrderAuthorization(orderAuthorization);
         Util.reloadBindings(window);
     }
+
+    public void setMessagesForUserComponent(IMessagesForUser component) {
+        messagesForUser = component;
+    }
 }
diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/users/OrderAuthorizationModel.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/users/OrderAuthorizationModel.java
index ad8db6755..56cdca829 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/users/OrderAuthorizationModel.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/users/OrderAuthorizationModel.java
@@ -47,25 +47,43 @@ public class OrderAuthorizationModel implements IOrderAuthorizationModel {
     @Override
     public List<OrderAuthorizationType> addProfileOrderAuthorization(
             Profile profile, List<OrderAuthorizationType> authorizations) {
+        List<OrderAuthorizationType> duplicated =
+            new ArrayList<OrderAuthorizationType>();
+        List<ProfileOrderAuthorization> existingAuthorizations =
+            listAuthorizationsByProfile(profile);
         for(OrderAuthorizationType type : authorizations) {
-            ProfileOrderAuthorization orderAuthorization =
-                createProfileOrderAuthorization(order, profile);
-            orderAuthorization.setAuthorizationType(type);
-            profileOrderAuthorizationList.add(orderAuthorization);
+            if(listContainsAuthorizationType(existingAuthorizations, type)) {
+                duplicated.add(type);
+            }
+            else {
+                ProfileOrderAuthorization orderAuthorization =
+                    createProfileOrderAuthorization(order, profile);
+                orderAuthorization.setAuthorizationType(type);
+                profileOrderAuthorizationList.add(orderAuthorization);
+            }
         }
-        return null;
+        return duplicated.isEmpty()? null : duplicated;
     }
 
     @Override
     public List<OrderAuthorizationType> addUserOrderAuthorization(
             User user, List<OrderAuthorizationType> authorizations) {
+        List<OrderAuthorizationType> duplicated =
+            new ArrayList<OrderAuthorizationType>();
+        List<UserOrderAuthorization> existingAuthorizations =
+            listAuthorizationsByUser(user);
         for(OrderAuthorizationType type : authorizations) {
-            UserOrderAuthorization orderAuthorization =
-                createUserOrderAuthorization(order, user);
-            orderAuthorization.setAuthorizationType(type);
-            userOrderAuthorizationList.add(orderAuthorization);
+            if(listContainsAuthorizationType(existingAuthorizations, type)) {
+                duplicated.add(type);
+            }
+            else {
+                UserOrderAuthorization orderAuthorization =
+                    createUserOrderAuthorization(order, user);
+                orderAuthorization.setAuthorizationType(type);
+                userOrderAuthorizationList.add(orderAuthorization);
+            }
         }
-        return null;
+        return duplicated.isEmpty()? null : duplicated;
     }
 
     @Override
@@ -184,4 +202,33 @@ public class OrderAuthorizationModel implements IOrderAuthorizationModel {
         this.order = newOrder;
     }
 
+    private List<UserOrderAuthorization> listAuthorizationsByUser(User user) {
+        List<UserOrderAuthorization> list = new ArrayList<UserOrderAuthorization>();
+        for(UserOrderAuthorization authorization : userOrderAuthorizationList) {
+            if(authorization.getUser().getId().equals(user.getId())) {
+                list.add(authorization);
+            }
+        }
+        return list;
+    }
+
+    private List<ProfileOrderAuthorization> listAuthorizationsByProfile(Profile profile){
+        List<ProfileOrderAuthorization> list = new ArrayList<ProfileOrderAuthorization>();
+        for(ProfileOrderAuthorization authorization : profileOrderAuthorizationList) {
+            if(authorization.getProfile().getId().equals(profile.getId())) {
+                list.add(authorization);
+            }
+        }
+        return list;
+    }
+
+    private boolean listContainsAuthorizationType(List<? extends OrderAuthorization> list,
+            OrderAuthorizationType authorizationType) {
+        for(OrderAuthorization authorization : list) {
+            if(authorization.getAuthorizationType().equals(authorizationType)) {
+                return true;
+            }
+        }
+        return false;
+    }
 }