diff --git a/openslides/core/static/css/app.css b/openslides/core/static/css/app.css
index c0392c4c0..bd4a1aa63 100644
--- a/openslides/core/static/css/app.css
+++ b/openslides/core/static/css/app.css
@@ -684,6 +684,16 @@ img {
     background-color: #317796;
 }
 
+.dropdown-entries {
+    white-space: nowrap;
+}
+
+.dropdown-entries > li {
+    padding: 5px 10px 5px 10px;
+    width: 100%;
+    cursor: pointer;
+}
+
 .slimDropDown {
     padding-left: 4px !important;
     padding-right: 4px !important;
diff --git a/openslides/users/static/js/users/site.js b/openslides/users/static/js/users/site.js
index 980b406d7..23ce966f2 100644
--- a/openslides/users/static/js/users/site.js
+++ b/openslides/users/static/js/users/site.js
@@ -98,6 +98,9 @@ angular.module('OpenSlidesApp.users.site', ['OpenSlidesApp.users'])
             resolve: {
                 groups: function(Group) {
                     return Group.findAll();
+                },
+                users: function(User) {
+                    return User.findAll();
                 }
             }
         })
@@ -646,10 +649,12 @@ angular.module('OpenSlidesApp.users.site', ['OpenSlidesApp.users'])
 
 .controller('UserImportCtrl', [
     '$scope',
+    '$q',
     'gettext',
+    'gettextCatalog',
     'User',
     'Group',
-    function($scope, gettext, User, Group) {
+    function($scope, $q, gettext, gettextCatalog, User, Group) {
         // import from textarea
         $scope.importByLine = function () {
             $scope.usernames = $scope.userlist[0].split("\n");
@@ -707,9 +712,17 @@ angular.module('OpenSlidesApp.users.site', ['OpenSlidesApp.users'])
         $scope.pageChanged = function() {
             $scope.limitBegin = ($scope.currentPage - 1) * $scope.itemsPerPage;
         };
+        $scope.duplicateActions = [
+            'keep original',
+            'override new',
+            'create duplicate'
+        ];
         // detect if csv file is loaded
         $scope.$watch('csv.result', function () {
+            // All user objects are already loaded via the resolve statement from ui-router.
+            var users = User.getAll();
             $scope.users = [];
+            $scope.duplicates = 0;
             var quotionRe = /^"(.*)"$/;
             angular.forEach($scope.csv.result, function (user) {
                 // title
@@ -735,6 +748,8 @@ angular.module('OpenSlidesApp.users.site', ['OpenSlidesApp.users'])
                 // number
                 if (user.number) {
                     user.number = user.number.replace(quotionRe, '$1');
+                } else {
+                    user.number = "";
                 }
                 // groups
                 if (user.groups) {
@@ -782,20 +797,102 @@ angular.module('OpenSlidesApp.users.site', ['OpenSlidesApp.users'])
                 } else {
                     user.is_committee = false;
                 }
+
+                // Check for duplicates
+                user.duplicate = false;
+                users.forEach(function(user_) {
+                    if (user_.first_name == user.first_name &&
+                        user_.last_name == user.last_name &&
+                        user_.structure_level == user.structure_level) {
+                        if (user.duplicate) {
+                            // there are multiple duplicates!
+                            user.duplicate_info += '\n' + gettextCatalog.getString('There are more than one duplicates of this user!');
+                        } else {
+                            user.duplicate = true;
+                            user.duplicateAction = $scope.duplicateActions[1];
+                            user.duplicate_info = '';
+                            if (user_.title)
+                                user.duplicate_info += user_.title + ' ';
+                            if (user_.first_name)
+                                user.duplicate_info += user_.first_name;
+                            if (user_.first_name && user_.last_name)
+                                user.duplicate_info += ' ';
+                            if (user_.last_name)
+                                user.duplicate_info += user_.last_name;
+                            user.duplicate_info += ' (';
+                            if (user_.number)
+                                user.duplicate_info += gettextCatalog.getString('number') + ': ' + user_.number + ', ';
+                            if (user_.structure_level)
+                                user.duplicate_info += gettextCatalog.getString('structure level') + ': ' + user_.structure_level + ', ';
+                            user.duplicate_info += gettextCatalog.getString('username') + ': ' + user_.username + ') '+
+                                gettextCatalog.getString('already exists.');
+
+                            $scope.duplicates++;
+                        }
+                    }
+                });
                 $scope.users.push(user);
             });
+            $scope.calcStats();
         });
 
+        // Stats
+        $scope.calcStats = function() {
+            // not imported: if importerror or duplicate->keep original
+            $scope.usersWillNotBeImported = 0;
+            // imported: all others
+            $scope.usersWillBeImported = 0;
+
+            $scope.users.forEach(function(user) {
+                if (user.importerror || (user.duplicate && user.duplicateAction == $scope.duplicateActions[0])) {
+                    $scope.usersWillNotBeImported++;
+                } else {
+                    $scope.usersWillBeImported++;
+                }
+            });
+        };
+
+        $scope.setGlobalAction = function (action) {
+            $scope.users.forEach(function (user) {
+                if (user.duplicate)
+                    user.duplicateAction = action;
+            });
+            $scope.calcStats();
+        };
+
         // import from csv file
         $scope.import = function () {
             $scope.csvImporting = true;
+            var existingUsers = User.getAll();
             angular.forEach($scope.users, function (user) {
                 if (!user.importerror) {
-                    User.create(user).then(
-                        function(success) {
-                            user.imported = true;
-                        }
-                    );
+                    // Do nothing on duplicateAction==duplicateActions[0] (keep original)
+                    if (user.duplicate && (user.duplicateAction == $scope.duplicateActions[1])) {
+                        // delete existing user
+                        var deletePromises = [];
+                        existingUsers.forEach(function(user_) {
+                            if (user_.first_name == user.first_name &&
+                                user_.last_name == user.last_name &&
+                                user_.structure_level == user.structure_level) {  
+                                deletePromises.push(User.destroy(user_.id));
+                            }
+                        });
+                        $q.all(deletePromises).then(function() {
+                            User.create(user).then(
+                                function(success) {
+                                    user.imported = true;
+                                }
+                            );   
+                        });
+                    } else if (!user.duplicate ||
+                               (user.duplicateAction == $scope.duplicateActions[2])) {
+                        // create user
+                        User.create(user).then(
+                            function(success) {
+                                user.imported = true;
+                            }
+                        );
+                    }
                 }
             });
             $scope.csvimported = true;
diff --git a/openslides/users/static/templates/users/user-import.html b/openslides/users/static/templates/users/user-import.html
index b20f36111..e54a9ff15 100644
--- a/openslides/users/static/templates/users/user-import.html
+++ b/openslides/users/static/templates/users/user-import.html
@@ -81,7 +81,7 @@
 
   <div ng-show="csv.result">
     <h3 translate>Preview</h3>
-    <table ng-if="!csvImporting" class="table table-striped table-bordered table-condensed">
+    <table class="table table-striped table-bordered table-condensed">
       <thead>
         <tr>
           <th>
@@ -95,14 +95,32 @@
           <th translate>Comment
           <th translate>Is active
           <th translate>Is committee</th>
+          <th ng-if="duplicates > 0" translate>
+            <i class="fa fa-exclamation-triangle text-danger"></i>
+            <strong class="text-danger" ng-if="duplicates == 1">1 Duplicate</strong>
+            <strong class="text-danger" ng-if="duplicates > 1">{{ duplicates }} Duplicates</strong>
+
+              <div uib-dropdown>
+                <button type="button" class="btn btn-default btn-danger btn-sm" uib-dropdown-toggle>
+                  <translate>Set global action</translate>
+                  <span class="caret"></span>
+                </button>
+                <ul class="dropdown-menu dropdown-entries">
+                    <li role="menuitem" ng-repeat="action in duplicateActions" class="pointer"
+                      ng-click="setGlobalAction(action)">
+                      <translate>{{ action }}</translate>
+                  </li>
+                </ul>
+              </div>
+          </th>
       <tbody>
         <tr ng-repeat="user in users | limitTo : itemsPerPage : limitBegin">
           <td class="minimum"
-              ng-class="{ 'text-danger': user.importerror, 'text-success': user.imported }">
-            <span ng-if="user.importerror">
+              ng-class="{ 'text-danger': (user.importerror || user.duplicateAction == duplicateActions[0]), 'text-success': user.imported }">
+            <span ng-if="user.importerror || user.duplicateAction == duplicateActions[0]">
               <i class="fa fa-exclamation-triangle fa-lg"></i>
             </span>
-            <span ng-if="!user.importerror && !user.imported">
+            <span ng-if="!user.importerror && !user.imported && user.duplicateAction != duplicateActions[0]">
               <i class="fa fa-check-circle-o fa-lg"></i>
             </span>
             <span ng-if="user.imported">
@@ -130,25 +148,41 @@
             <div ng-repeat="groupname in user.groupnames">
               {{ groupname | translate }}
             </div>
+          <td style="max-width: 130px;">
+            <span uib-tooltip="{{ user.comment }}">
+              {{ user.comment | limitTo: 30 }}{{ user.comment.length > 30 ? '...' : '' }}
+            </span>
           <td>
-            {{ user.comment }}
+            <i class="fa pointer" ng-class="user.is_active ? 'fa-check-square-o' : 'fa-square-o'"
+              ng-click="user.is_active = !user.is_active"></i>
           <td>
-            <i ng-if="user.is_active" class="fa fa-check-square-o"></i>
-          <td>
-            <i ng-if="user.is_committee" class="fa fa-check-square-o"></i>
+            <i class="fa pointer" ng-class="user.is_committee ? 'fa-check-square-o' : 'fa-square-o'"
+              ng-click="user.is_committee = !user.is_committee"></i>
+          <td ng-if="duplicates > 0">
+              <div ng-if="user.duplicate" uib-tooltip="{{ user.duplicate_info }}" uib-dropdown>
+                <button type="button" class="btn btn-default btn-sm"
+                  uib-dropdown-toggle ng-class="user.duplicateAction == duplicateActions[0] ? 'btn-warning' : (user.duplicateAction == duplicateActions[1] ? 'btn-danger' : 'btn-success')">
+                  {{ user.duplicateAction }}
+                  <span class="caret"></span>
+                </button>
+                <ul class="dropdown-menu dropdown-entries">
+                    <li role="menuitem" ng-repeat="action in duplicateActions" class="pointer"
+                      ng-click="user.duplicateAction = action; calcStats()">
+                      <i class="fa fa-check" ng-if="user.duplicateAction == action"></i>
+                      <translate>{{ action }}</translate>
+                  </li>
+                </ul>
     </table>
     <uib-pagination total-items="users.length" items-per-page="itemsPerPage" ng-model="currentPage" ng-change="pageChanged()"></uib-pagination>
 
     <div class="text-danger">
-      <div ng-repeat="user in usersFailed = (users | filter:{importerror:true})"></div>
       <i class="fa fa-exclamation-triangle"></i>
-      {{ usersFailed.length }}
+      {{ usersWillNotBeImported }}
       <translate>participants will be not imported.</translate>
     </div>
     <div>
-      <div ng-repeat="user in usersPassed = (users | filter:{importerror:false})"></div>
       <i class="fa fa-check-circle-o fa-lg"></i>
-      {{ users.length - usersFailed.length }}
+      {{ usersWillBeImported }}
       <translate>participants will be imported.</translate>
     </div>
     <div ng-repeat="user in usersImported = (users | filter:{imported:true})"></div>
@@ -160,11 +194,11 @@
     </div>
 
     <div class="spacer">
-      <button ng-if="!csvImporting" ng-click="clear()" class="btn btn-default" translate>
+      <button ng-click="clear()" class="btn btn-default" translate>
         Clear preview
       </button>
       <button ng-if="!csvImporting" ng-click="import()" class="btn btn-primary" translate>
-        Import {{ users.length - usersFailed.length }} participants
+        Import {{ usersWillBeImported }} participants
       </button>
     </div>
     <div class="spacer">