well, the API does not say it will return the name of the created object...
but i agree with you that it should do it!
could you please fill a feature request to make sure that it will be done in the new scripter engine (which is currently being finished...)
for the time being, you can use the following workardound:
<pre>
scribus.duplicateObject();
newItem = scribus.getSelectedObject();
</pre>
... after duplicating the item, scribus automatically selects the newly created one... (which is or is not what it should do... imo, it should not to do it, since it's a side effect... a mostly welcome one, but still a side effect!)