automatically show duplicated reference when add a new one

If I add a new reference, I want endnote should give me a suggestion whether the newest added one have duplications in the library.

Thank you.

Great suggestion.  the only way I manage this currently, is to add new refs into an empty library and import that temporary library into my own library (with the discard duplicate check option).  – I would love it, if the simple act of adding it to the  library invoked such a screen!