Yes. The certificates need to be renewed before they expire, so Cloudflare generate a new certificate, and then replace the certificate before the old one expires. There always needs to be some overlap, otherwise the would not have time to deal with issues at the CA, or other issues with deploying the new certificate on their infrastructure.
So what should I do now?
The certificate CloudFlare sent to me via Certificate Transparency Notification have a different valid date with the current one show in my website (vnkeyfc.com), as I said above. I am verry worrying that there is problem with my website’s SSL.