Search word - multiple
If the loan is secured by multiple properties (purchase or refi), pick one and report on it.
In a HI, you report on the property be improved. If more than one property being improved, pick one.
One clarification "Even if you took both of them as collateral, if they're each a 1-4 family unit, you report 1-4." In your case, one of these would be reported as a 1-4, the other would be reported as a code 2-manufactured housing, depending on which one you selected.