How does Deduplicator choose which contact to keep?

I am a noob at eM client and am trying to deduplicate my contacts.  I have 3 sources: iCloud, yahoo webmail  contacts and a local file.  Many, many contacts appear in triplicate but I know of the repeats, some have more recent emails or phone numbers than others.  I saw in another thread that Deduplicator identifies duplicates by name, but once say, 2 or 3 contacts are identified as duplicate or triplicate by name, how does Deduplicator then choose which one to keep?  Is it by date most recent (which is best for me), or some other criteria?  If so, what is the criteria?

Hi, if you use the deduplicator, you can choose whether duplicate contacts are merged, moved or deleted. If you select the option to delete them permanently, there will be a window showing the results, if deduplicator finds a duplicate there will be (1 contacts merged - the text is actually wrong at the moment, will be fixed soon), if you click on that link you can choose which one will be deleted and which one will be kept manually, but otherwise deduplicator just picks one.

You can also select the items to merge in the results window.

Hope this helps,
Paul.