Editable menu creates items when clicking on parent

Reproduction path:

1. create a new project from the archetype and add the news and simple-content from essentials
2. open the cms in the channel manager and edit, open the menu
3. create a new item with label search with destination none
4. create a new item with label google and destination external with value https://www.google.com
5. make the item google a subitem of search
6. now click on search and then google and then again search

Executing the last step creates a few more search and google items. The attached image shows the issue.
The problem seems to be only visual and if you close and save the changes, the new extra items will not be persisted. Opening again the menu in edit mode will find the situation in a good shape.