XML data on component TREE, show duplicated childs on Internet Explorer

If you open this Webix examples on Internet Explorer:
http://docs.webix.com/samples/17_datatree/01_loading/02_xml_data.html

At first example show duplicated childs. At this snippet also happens the same problem:
http://webix.com/snippet/69b7a9e8

It could be treat as a bug?

Regards

Problem confirmed

The same problem was fixed by previous update in IE9-IE10, but it still occurs for latest IE11 and IE12. Fix will be included in the next build.
If you need it asap - please open support ticket.