PS_EMAIL_ADDRESSES OTHR question

Hello,

We are seeing something strange with our email addresses, and I wonder if someone can shed some light for me.

In ps_email_addresses - our employees have HOME and BUSN. BUSN is the preferred email, because it's the company email. We are seeing new OTHR emails for some employees, with the exact same email address as the BUSN. They aren't being entered online. We've been deleting the OTHR duplicate, but it comes back after some time.

Any idea what is causing these OTHR email addresses to get entered, with the same address as BUSN? Is there some automatic process happening that we are not aware of?