When I export a contact of Google Contacts in Google CSV format and import it again without changing the file, I get two exact the same contacts. Google can not find it in Duplicates:
https://contacts.google.com/merge
Background: I have a website that creates that CSV also and after import it created many duplicates. I tried to solve it and found out that a simple export and import creates the same problem. Is it a bug in Google Contacts or can I do something to solve this problem?