Summary: A custom field can be created to track additional email addresses, but there is no automation of secondary email address.
There is a way one could add an additional email address for a candidate; Jobvite Administrators have the ability to add any sort of custom field in the Candidates tab, and this could be done with a text-based field titled Secondary Email Address, for example.
This would add a field to the Candidate Details section of the Summary tab in the candidate's profile, where you could then add/track an additional email address.
Note: While it is possible to add additional fields for tracking non-primary email addresses, this is not considered best practice. All messages going to the candidate will be routed only to 1 email address - the address that appears in the default field entitled Email Address. Any off-record communication with a candidate is not recommended; therefore, best practice is to always maintain the default Email Address field with the most up-to-date or preferred address of the candidate.