What happens with new contacts coming from chats when email address sharing is enabled?

Environment:

Chat, Email Address Sharing, householding
Oracle B2C Service 

Issue:

We have email address sharing enabled for contacts. When a chat comes through, if there is an existing contact record, then the chat will correctly apply itself to the correct contact. However, when a brand new contact comes in via chat with the same email address, rather than create a new contact record, the chat is allocating itself to the latest contact record created under the same email address. 

Resolution:

This behavior is expected. As with other areas of the product, when the appropriate contact cannot be identified, by means of name or login information, the contact ID last updated in the database will be the one associated to the chat. By default, when Email Address Sharing is enabled, the Email field on the chat sessions workspace will display a yellow icon with a black exclamation point if a duplicate email address is detected by the system. The agent can then manually change the contact association by clicking the Contact field and selecting Change.

Note:  When looking at the values for the name and email fields present in the chat workspace, you should keep in mind that the information from the 'chats' table may be different than the one from the 'contacts' table. With email address sharing, the yellow icon with a black exclamation point will only be present for the field 'Chat.Email', which is also the one present in the standard chat sessions workspace. If you have chosen to replace the field 'Chat.Email' with the 'Contact.Email' field in your chat workspace, the yellow icon showing the duplicate contact will not be visible.

For more information on contact-matching logic, please see Answer ID 2831: Householding - email address sharing.