Same email in more than one lead, not unique

Email is set as the unique identifier and yet I have two leads with the same email address. How is this possible? Is this a bug? I am on version 2.0.1

Email is set as the unique identifier and yet I have two leads with the same email address. How is this possible? Is this a bug? I am on version 2.0.1

How were the contacts created? Mautic allows to create a duplicate contact via the administration. It may be a feature for one person and a bug for another. Hard to say.