diff --git a/plugins/calendar/lib/calendar_ui.php b/plugins/calendar/lib/calendar_ui.php
index 37b7b44d..79b631d7 100644
--- a/plugins/calendar/lib/calendar_ui.php
+++ b/plugins/calendar/lib/calendar_ui.php
@@ -513,6 +513,7 @@ class calendar_ui
     }
 
     $input = new html_inputfield(array(
+        'id'     => 'importfile',
         'type'   => 'file',
         'name'   => '_data',
         'size'   => $attrib['uploadfieldsize'],
@@ -533,7 +534,7 @@ class calendar_ui
     $html = html::div('form-section form-group row',
       html::label(array('class' => 'col-sm-4 col-form-label', 'for' => 'importfile'), rcube::Q($this->rc->gettext('importfromfile')))
       . html::div('col-sm-8', $input->show()
-        . html::div('hint', $this->rc->gettext(array('id' => 'importfile', 'name' => 'maxuploadsize', 'vars' => array('size' => $max_filesize)))))
+        . html::div('hint', $this->rc->gettext(array('name' => 'maxuploadsize', 'vars' => array('size' => $max_filesize)))))
     );
 
     $html .= html::div('form-section form-group row',
diff --git a/plugins/tasklist/tasklist.js b/plugins/tasklist/tasklist.js
index 7853df3f..731e56c2 100644
--- a/plugins/tasklist/tasklist.js
+++ b/plugins/tasklist/tasklist.js
@@ -862,6 +862,16 @@ function rcube_tasklist_ui(settings)
         loadstate.lists = active_lists();
     }
 
+    var init_cloned_form = function(form) {
+        // update element IDs after clone
+        $('select,input,label', form).each(function() {
+            if (this.htmlFor)
+                this.htmlFor += '-clone';
+            else if (this.id)
+                this.id += '-clone';
+        });
+    }
+
     // open a dialog to upload an .ics file with tasks to be imported
     this.import_tasks = function(tasklist)
     {
@@ -876,6 +886,8 @@ function rcube_tasklist_ui(settings)
         if (tasklist)
             $('#task-import-list').val(tasklist);
 
+        init_cloned_form(form);
+
         buttons[rcmail.gettext('import', 'tasklist')] = function() {
             if (form && form.elements._data.value) {
                 rcmail.async_upload_form(form, 'import', function(e) {
@@ -939,22 +951,22 @@ function rcube_tasklist_ui(settings)
     this.export_tasks = function()
     {
         // close show dialog first
-        var $dialog = $("#tasksexport").clone(true).removeClass('uidialog'),
+        var list, $dialog = $("#tasksexport").clone(true).removeClass('uidialog'),
             form = $dialog.find('form').get(0),
             buttons = {};
 
         if ($dialog.is(':ui-dialog'))
             $dialog.dialog('close');
 
-        $("#task-export-list").val('');
+        list = $("#task-export-list").val('');
+
+        init_cloned_form(form);
 
         buttons[rcmail.gettext('export', 'tasklist')] = function() {
-            var data = {},
-                source = $('#task-export-list').val(),
-                form_elements = $('select, input', form);
+            var data = {}, form_elements = $('select, input', form);
 
             // "current view" export, use hidden form to POST task IDs
-            if (source === '') {
+            if (list.val() === '') {
                 var cache = {}, tasks = [], inputs = [],
                     postform = $('#tasks-export-form-post');
 
diff --git a/plugins/tasklist/tasklist_ui.php b/plugins/tasklist/tasklist_ui.php
index c1ac9081..fd999898 100644
--- a/plugins/tasklist/tasklist_ui.php
+++ b/plugins/tasklist/tasklist_ui.php
@@ -500,6 +500,7 @@ class tasklist_ui
         }
 
         $input = new html_inputfield(array(
+                'id'     => 'importfile',
                 'type'   => 'file',
                 'name'   => '_data',
                 'size'   => $attrib['uploadfieldsize'],
@@ -509,7 +510,7 @@ class tasklist_ui
         $html = html::div('form-section form-group row',
             html::label(array('class' => 'col-sm-4 col-form-label', 'for' => 'importfile'), rcube::Q($this->rc->gettext('importfromfile')))
             . html::div('col-sm-8', $input->show()
-                . html::div('hint', $this->rc->gettext(array('id' => 'importfile', 'name' => 'maxuploadsize', 'vars' => array('size' => $max_filesize)))))
+                . html::div('hint', $this->rc->gettext(array('name' => 'maxuploadsize', 'vars' => array('size' => $max_filesize)))))
         );
 
         $html .= html::div('form-section form-group row',