Plugin contact name as identifier?


I have a little question about plugin contact.
I am trying to use this plugin with my LG G4.
I noticed that when I try to store a contact with the same name but different phone numbers (manually in my phone) the new contact is well created.
However when I try to create it with the plugin the new contact is not created. Is it normal behavior?
Should I use the full name as unique ID.
Maybe it is a restriction because not allowed to have duplicates on some phones.

Do you have suggestion?

Best regards

Geoffrey MUSELLI