I was hoping that you might be able to provide some feedback.  We are currently using Commerce 12.17 and (a few times per week) we are getting contact records where firstname and lastname are populated with the customer's email (username) and the email field is blank.  

We can find no place that this is happening programatically; and we have pretty extensive frontend and backend coverage to make sure that we wouldn't be able to pass an empty email address in at-all (For the _clsContact records in question the value for email is an empty string; not null).  The create and modified dates are the same; and typically we don't populate first or last name at-all (they typically get updated later).

We utilize ... Mediachase.Commerce.Customers ... CreateInstance and SaveChanges pretty extensively.

We started having these issues around October; not sure if it coencided with an upgrade on our part or not.

This below issue calls out out the same exact issue that we are having (not sure if it is something that was fixed or noted in an update) ...

https://world.episerver.com/forum/developer-forum/Episerver-Commerce/Thread-Container/2018/10/applicationuser-user-and-customercontact-are-created-automaticlly-commerce-12-8/

Thanks in advance for your thoughts and input on the matter

Dan DiNardo (Turn5)