Duplicate email address with Email Address Sharing disabled

Content

Hello,

We have Email Address Sharing disabled, but still, we have a number of contacts with same email address (sent by API integration from a platform). The email address is corect, without 001 and the Primary Email invalid is set to No.

Is there an explanation for this behavior? How can we automatically set incidents and orders of every duplicated contact to only one of the duplicated contacts and delete the others?

Thank you!