Hi,

as I try to import a node with the same title, the module answers correctly: 

Can not import this node. Check following errors:

    * The node title XXXXXXXXXXX is not unique for this node type.

If I go further, I obtain:

    * There was 1 error. Click 'Download rows with errors' for a CSV file of the failed rows.
    * Successfully imported 0 nodes.

*BUT*, if I search content, I find the new node duplicated!

So, warning/error messages are correct, on the contrary the output isn't coherent.