.vcf not importing all of the 3476 contacts but 978

First of all, Hello guys!

I wanted to share a problem that I'm facing with. My cousin had a some oldy samsung duos phone(cant remember exact model). So he used it for business. He has over 3400 contacts in it. He got a new phone, and now he asked me to transfer his data, documents etc to the new phone(which I did). Everything went fine expect contacts. I used laptop and MobileGo by Wondershare application to do a manual back of everything he needed. When I exported all the contacts to a .vcf file. He had 3476 contacts al togheter. When I imported that .vcf file to a new phone(also samsung j5 j500), it said that import finished successfully but there are only 978 contacts. There were some duplicate(on the old samsung as well, but not as much to lower contact list from 3400+ to <1000).
He isn't that much into phones,so he didnt use sync option to sync with gmail or something similar.

Can you guys help me,please? I ran out of ideas how to fix this..

Best regards,
Nikola