Duplex as a primary residence

[Candice Cervantes]

Hello! I’m looking into buying a duplex as a primary residence. One of the units is currently rented under market value. The other unit is vacant. Since Portland is such a tenant friendly city, I’m wondering if there is a loop hole or if I can choose the occupied unit to move into in an effort to rent the other at market value? Or would I be required to take the vacant unit? Thank you!