HMDA -Second Applicant Considered a "Co-borrower"?

Regarding HMDA reporting of government monitoring information for a co-applicant received on a separate loan application. Commonly, when unrelated borrowers apply for a mortgage loan, they fill out separate 1003 loan applications. Also commonly, most mortgage lending institutions and their lending systems treat the two applications as a single "loan". HMDA reporting is then done on a "loan" level. In this case, would the second applicant be considered a "co-borrower" and would their government monitoring information be reportable to HMDA under one (the same) "loan"?