removed not unique warning from attributes dialog as it's more common to have multi value

src/views/index.ejs

@@ -620,7 +620,6 @@
                 <td>
                   <!-- Change to valueUpdate: blur is necessary because jQuery UI autocomplete hijacks change event -->
                   <input type="text" class="attribute-name form-control" data-bind="value: name, valueUpdate: 'blur',  event: { blur: $parent.attributeChanged }"/>
-                  <div style="color: yellowgreen" data-bind="if: $parent.isNotUnique($index())"><span class="glyphicon glyphicon-info-sign"></span> Duplicate attribute.</div>
                   <div style="color: red" data-bind="if: $parent.isEmptyName($index())">Attribute name can't be empty.</div>
                 </td>
                 <td>